Not much has improved for locks, so few changes to my suggestions:
Destruction:
-Chaos Bolt is meagre, and needs a buff. I've been using DrDamage to monitor its theorycrafted damage output, and it's barely a few hundred points above Incinerate. For a spell on a 12 sec CD, it's weak. It should go back to piercing all immunities/absorptions as well as reflects and the like. In addition, there was a suggestion to make hit rating over a certain point add bonus damage to the spell, to replicate its piercing effect in PVE. For PVP, this could scale with Spell Penetration. Either way, it needs much higher damage. Perhaps guaranteed crits if Conflagrate was used in a time period would also work.
-Overall destruction's dps output in PVP is a bit low, though its main focus is sheer speed over single high damage nukes. It still needs a review, particularly Immolate's sensitivity to dispels and the amount of interrupts flying about. Potentially move damage from the Imp and Corruption to other nukes in the spec. A redistribution away from dots and back to direct damage would be ideal. Destro has never been the epitome of a dot spec.
-Removal of Corruption from destro's PVE rotation. It ill fits the spec. Destro isn't made harder by another dot (in a DD fire spec) but clunkier. Instead, buff Empowered Imp to compensate. This won't lead to being OP in PVP as SF doesn't even hit so hard. If buffed to reliably proc SF when SB isn't off CD it'll also ease maintenance of ISF.
-A possible defensive mechanism like Barkskin for melee protection, could trigger for instance if you're stunned twice in a row.
-Immolate direly needs some form of dispel protection, or even made undispellable. It's destro's main source of damage, as without it Incinerate hits even less hard, you cannot cast Conflagrate and you lose a fairly high DPCT spell from the target. It's not like any of these spells save Conflagrate hit very hard as it is, and even in its case, it's nothing phenomenal at all. Alternatively: let dispelling it do something like reset the CD for Conflagrate or SF or make BoD hit like a ton of bricks in one go. Or spread a dot. Just make it hurt. Dispelling isn't as idiot proof as it was a while ago but it's still lethal to destro.
-Backdraft made undispellable, like FoF.
-A talent converting BoD to fire damage, or felfire even (call it Baleful Flames or something.) Possibly Burning Embers. I'd like Demonology to be the shadow/fire spec and the other two more specialised in their domains. Additionally, for Destro BoD could have a small chance to disorient on each tick, an idea I saw suggested here.
Affliction:
-CoEx going back to 30% makes it borderline useless. There's no two ways about this. If the spell was deemed to strong, a more sensible solution would be to limit the number of targets it could have and/or put a small CD on it. When other classes have more powerful snares baseline in their main nuke, one wonders what it is that made this one, finally useful spell, OP?
-Give Shadow Bolt a Soul Burn effect that reliably procs Eradication and makes it instant, simulating the mechanics with shadow spells. Affliction needs a big damage boost right now.
-Buff Drain Soul damage. The execute filler is very weak.
-Change Nightfall to buff Drain Life, effecting a nuke switch similar to SB -> Incinerate with MC. Nightfall currently doesn't change much. It's instant damage, but like the old Empowered Imp, it's boring, and you cannot rely on it to refresh SE for movement phases. Possibly change its filler to Drain Life and make it rely on instant Shadow Bolt procs instead. Consider making SE a self-buff. The spec's damage is not high enough for this to be deemed OP at the moment since most of its power comes in the form of high survivability, not damage.
-Unstable Affliction. Maybe implement a mana burn feature in it (idea courtesy of Jessicka.) Its damage is still on the low end.
-A suggestion for Drain Mana (courtesy of Gaahl on the EU lock forum) is to let it have DR, reducing its effectiveness the more it's used but allowing us to keep it in our arsenal. Very few locks are satisfied with the loss of this spell.
-Subject its Demon Soul (felhunter) to a re-evaluation. Fact that it doesn't apply to existing dots is an issue.
Demonology:
-Its execute is weak. This also ties into Soul Burn having very little PVE use for the spec. Perhaps let Soul Burn function with Demonic Empowerment (spell we rarely if ever use in PVE) to give a temporary buff to demon damage when activated together. I know Blizzard aimed to reduce its dependence on its execute nuke but I think they overstepped the mark a little. Maybe let MC affect SF again and buff it when it procs.
-Improve MC's proc rate slightly.
-Demo is mostly good right now. Its single-target damage received a mild buff and it still puts a lot of weight on Metamorphosis, but I don't think the spec has any serious design flaws worth noting. Its talent spec is somewhat forced in how much freedom for variation you enjoy and how many low tier talents add much to the leveling experience and this is a flaw mirrored with affliction and to a lesser extent destro, but not gamebreaking.
-Green fire for Soul Fire and Immolation Aura. Cosmetic but nice.
Pets:
-Succubus needs a buff and to be brought in line back to being a good PVP pet. IIRC, haste does not affect Seduction (a spell which, I might add, shares DR with Fear as it is.) Whiplash is nice for getting melee off you, but why use the Succubus over the Imp with Singe Magic or the Felhunter with offensive dispels? Her Demon Soul could focus on PVP usages, perhaps giving a disarm effect with a 5 - 10 sec ICD for the 20 secs it's active (so it wouldn't be notably more powerful than Psychic Horror), as well as a more universally useful buff than a damage bonus to SB. I'd like to see some sort of talent reducing Seduction's cast time as well as haste affecting it (if it doesn't, I've not been able to get a clear answer on this), and for her to return to being the Warlock's choice for melee. I was perfectly happy with our existing pet selection. Do they really think throwing in another pet for its own sake was a good idea?
-Drop the Imp from PVP (or give it some different utility), and revert defensive dispels to the Felhunter (reason behind its recent nerf to begin with.) This was never so much a nerf as much as the silly notion that we should be forced to vary our pet usage more. Yet now we're stuck with even more useless pets, when other classes get our abilities baseline. Granted, pet summoning is easier, but still not costless. Offensive/defensive dispels shared a CD anyway. Revert DM to an 8 - 10 sec CD. I fail to see how this was OTT.
-Sacrifice made into a baseline Warlock ability, retains 1 min CD. Possibly, let SB/HS trigger the effect instead of what it does now. It's not very powerful as it is, requires a pet switch and is on a 1 min CD. The VW serves precious little other purpose.
-A melee range interrupt for the FG on a slightly higher CD than the FG's. Demo's main feature is its more powerful pet, and I don't see this as making the spec too powerful as its anti-caster tools aren't very great. Possibly a disarm too, but on a higher CD than the Succubus's if she got one as well.
General:
-Make Demonic Circle: Teleport targettable and/or instant. If this is prone to abuse, just don't let it be targetted in certain areas and make SB give the target effect. Possibly let it "remove" the Warlock from being selected like Mirror Image does with Mages. Adjust range as necessary.
-Make SL automatically on, passively, and give the ability to clear the buff. Possibly design it as an aura effect on the pet's toolbar.
-If the Succubus is not redressed, a stunbreaker. She used to function as the equivalent of one. Perhaps one where you swap spots with your pet.
-Shadowflame glyph becoming baseline. I remember on the PTR there was a version of it that had a small Horror effect appended, but I'm not sure this is the right spell to attach that too. A possibility would be for Soul Burn to give it that effect? That way, you lose other uses for it but gain additional CC.
-Extend Soul Burn's utility.
-Give a 2 - 3 min CD spell that lets you use Soul Harvest in combat. Mages can regenerate their most important resource, mana, in combat, as well as HP. Intelligent use of CC would mean we can at least heal a bit more in combat, and get back those important SS's.
-Buff Fel Flame's damage somewhat. It hits for incredibly little.
-Potentially reduce demonic guardian CD, even if only for demo, so that it's usable on a more frequent basis in instances.
-Put interrupts on shared DR. Something like Rift's location check only being enforced at the beginning of casts would also be cool, so melee can't just exploit the lack of realistic physics to run through to avoid spells being cast.
-Fel Armor nerf has hit demo and destro hard, reducing their survivability. Consider letting each talent it (destro via Soul Leech, demo via another talent) to restore passive healing to the spell. If affliction needs nerfs to self-healing, they should be isolated specifically to that spec, not in an across-the-board fashion.
So anything you guys would add? Any thoughts on these? I say this is a conservative wishlist because I'm asking for some nerfs (which weren't even really intended explicitly as such) to be reverted. Overall, I'm very happy with the class in PVE. In PVP it could do with some tweaks, primarily with respect to pets.
Edit: Formatting/additions.
Edit 4: Some minor changes.