I came into this expecting to see someone make a post to help all of the Warlock FOTM Destro re-rollers from 5.4, who can't play demo, plan their movement. I should have known better but I din't see the sunglasses! haha
For real though it's shocking how many people don't know that dropping RoF is a DPS increase over doing nothing lol. A guy in my guild recently swapped to his lock from his mage and he wasn't casting RoF while moving because "there was no AOE". Was just sitting there doing nothing on the run.
In my experience with Mythic after patch, Destruction is just fine really. Sorry, but there is not that much movement really if you know where to stand and the movement there is, is usually nothing more than a couple of seconds of movement really.
As fact, I'd say Destruction is just as it was - pure single target it's okay, but the moment things like adds come out which can be exploited for milking Havoc Shadowburns or straight out AoE (and almost EVERY Mythic fight has either of those or even both) - Destruction is back on bloody top there in my experience.
Also, as I have personally tested Demonology right now is retarded powerful though - Chaos Wave is too strong, so it's stronger than Destro quite a bit especially in 5 man content where 2 Chaos Waves are enough to demolish packs of adds in literally 3 seconds, but it gets (rightfully) nerfbatted now, so I guess it will be back to Destro levels (I'd say a bit lower now than Destro now), which are pretty damn fine as a matter of fact, since Demo has 0 movement issues really.
As a matter of fact, current Destruction reminds me A LOT of TBC's Sacrifice/Ruin (well except that you have a bit more than like 2 buttons and it's a bit smarter too). Movement issues are one to one really, but with things being tuned right, I am sure Destruction will be just as powerful if not more by the grace of Havoc and Shadowburn.