I want some kind of secondary resource but it probably won't happen. Here's why.
There's limited number of ways to make a rotation:
1) Procs. We have too many of them already.
2) Spells on short sooldowns which have high damage/buff damage/put debuff on enemy. Long cooldowns don't count. The example of cooldown-based class is Enh Shamans. I would say that right now Shaman is the only class that works almost entirely on this model, other classes have mix of different ways to make a rotation.
3) DoTs. Essentially this is a variation of the previous case. Difference is that DoT doesn't have a cooldown, but it's useless to spam it, you have to wait for DoT to end (or at least for half of it's duration to expire in case of Warlocks). The relation between DoT and spells on cooldowns is further revealed by pairing of 2 DoTs and cooldown in level 75 talent tier (Frost Bomb vs Living Bomb/Nether Tempest). Also historically Mage is not a DoT class so I don't like this direction for us.
Mages are enforced to use existing DoTs. First of all by Pyromaniac debuff for Fire Spec and Brain Freeze proc for Frost spec. Finally in April bombs were buffed by 40%.
4) "Skillshots" = excessive clicking. This is a case with Rune of Power, Power Crystal and Meteor. You need to click on the spell button, choose a place for it, then click on it. First implementation of RoP while theoretically interesting was horrible for me. Power Crystal and Meteor is more of the same. I keep wondering why developers keep going this way for Mages and not other classes: excessive clicking feels very artificial and awkward in single target rotation. Also other classes lose that mechanic. Lighwell became Lightspring, Hand of Gul'Dan now requires selecting a target instead of the area and only Mages are left with "stop what you're doing and aim for something on a screen" button in their single-target rotation.
5) Limited resource. It's Rogue, Warrior and Hunter model. Developers tried to implement it for Destro Locks with Chaotic Energy but it doesn't really work and needs more tight tuning. Arcane mana management is a variation of this system.
6) Secondary resource management. Realistically the best model what allows diversification. Devs are able to make more complex rotations and priorities for players. It's interesting that Mages got some sort of clone of those mechanics that didn't quite work because we don't actually have secondary resource. The different ways to use secondary resource are:
a) Competition between self buff and damaging ability. It's a choice between Inquisition and Templar Verdinct for Paladins, Slice and Dice and Eviscarate/Rupture/etc. for Rogues and other option for other classes.
Mages actually got two variations of this mechanic. First one is Cata version of Arcane there Mages got to choose between buff from high amount of Mana and burst from 4 stacks of Arcane Blast. Second one is Invocation in 5.0 version. Both of them didn't actualy work that well because insted of spending secondary resource Mage are constrained by timing of Evocation, and Mages have no way to change Evocation cooldown whereas other classes can receive secondary resource. Since Evocation in both cases has same cooldown, it makes rotation feel very Metronomic and predictable whereas secondary resource allows choice and mistakes.
b) Storing up and spending of the resource. Best example is Demo Lock, next on is Destro lock. I would say that this model is more successful younger brother of Arcane mana spending model (once again, secondary resource is better constraint then fixed cooldown of Evocation).
c) Soft cooldown. Building up combo points means that you can't spam big nukes and finishers, so effectively they are on coldown, but it's defined not by time per se, but by users actions. Hides the cooldown from user and makes him responsible for big/meaninful abilities, creates more interesting gameplay.
d) Interaction of resources Rune spending increases Runic Power, spending Energy builds up Combo Points.
I probably forgot something but for the moment that's all I can think of.
Now to Mages. It seems to me that Blizzard is in a corner with Mage class design. We know that devs want to make a rotation more complicated and level 90 talents were an attempt to do that, but now that they are (hopefully) gone, there must be something new to add to our spellbooks.
Let's look at the things class designers can do. Devs don't want to spend much time on design and new secondary resource-related work is a huge time-eater. Also it seems that they don't want to touch core mechanics (2 mechanics per spec) and just want to add some buttons to make rotations more complicated. But again, they don't want to spend much time on Mages - band-aidish updates such as level 90 talents (which are really a rehashes of some machanics of two-resource classes with a twist), obligatory DoTs and addition of multiple "skillshots" i.e. click-and-aim-and-click-and-maybe-click-one-more-time-just-to-use-one-ability buttons show this.
So I wonder what will devs do? Implement some spells on cooldowns in addition to procs? Add more DoTs? Will they increase number of charges of Pyroblast!, Magic Missiles, Brain Freeze or Fingers of Frost (oh, Demonology rip-off, sacrilege)? Or allow some abilities to decreas cooldwns of others? Or maybe make Mana Gems an Arcane Resource with shorter cooldown and some regeneration incombat mechanic? I'm eagerly waiting for what Blizzard will offer in WoD.