There was lots of recent chatter on the old school blogs about 'dissociated mechanics' and how this doomed 4E. The hanging question, is WOTC still doing the same thing in 5E?
I have a different requirement for 5E: I want a set of rules that support simulation of whatever fantasy world I'm building for my campaign.
I know the word "simulation" is loaded; I don't want a game that simulates real world physics. But I want the rules that define the game elements to follow some internal consistency, and apply equally to players and non-player characters and the world at large. I want a rules set that is coherent for simulating an interesting D&D world for placing adventures.
4E is littered with examples where the rules of the game lead to a game setting that has zero internal consistency or logic. Monsters have ridiculous armor classes that make them impossible for the ordinary inhabitants of the game world to damage them. Other monsters have 1 hit point each (as minions) and die when someone gives them a good push.
Just look at the subjective logic of treating dragons as "solo monsters" in some instances, or "elites" based on the combat role the DM wants them to possess, in the next. The monster has no objective reality in the setting; its role and mechanical footprint is completely subjective, and based only on how it's defined in relationship to the chosen ones, the player characters. I wouldn't be surprised if there were eventually dragon "minions", too.
I was stubborn with that game system - we gave it a long leash, trying multiple campaigns and getting deep into the 'paragon tier', against my better judgment. I drank multiple cups of the kool aid. I won't be nearly so gullible with 5E.
So this is my personal criteria for a successful 5E. The rules and mechanical bits need to present a world with internal consistency regardless of the presence of player characters. The mechanical styling of a 4E game world only made sense when viewed from the perspective of providing a perfectly balanced challenge for a set of player characters of superheroic stature with manifest destinies. It was basically West World, Future World, and any one of those Yul Brenner theme parks (Medieval World, Roman World). It drove me nuts.
I haven't looked that closely at 5E yet to know if it passes the test. We probably haven't seen enough regarding the roles of monsters and NPCs in the setting. I've heard the buzzword "bounded accuracy", which seems to mean The Mearls has abandoned scaling armor class and gone back to the older approach, where armor classes exist in a consistent range across the game setting. That's really a great first step. But I've also heard that level 1 characters have super high hit point totals and wield the crazy at-will powers. (Like, dude, where's my first level?). If NPC opponents have the same ridiculous hit points and the laser-beam clerics and the zap zap zap wizardy powers, then perhaps the system will have some internal logic. It might be a good system for gonzo high magic fantasy where all the clerics walk around shooting lasers out of their holy symbols and all the wizards shoot ice rays out of their fingers, and that's just how the world works.
I don't see that happening; I have to think the final version of 5E will keep the players as the super heroic chosen ones of destiny, with over-the-top abilities no one else in the game world seems to possess. This will probably mean I'll skip 5E entirely. I can live with some dissociated mechanics. I won't buy into another incoherent WOTC game that panders to power gamers. I truly hope to be proven wrong!