I think I'm starting to see some of the signs of 4.5 or 5E, but nothing nearly significant enough to say that it's expected. The main 'patching' issues I'd expect from a 4.5E would be these:
1) Cleric, Paladin, and Ranger adjusted to be like the other classes (single primary ability score, option of secondaries).
2) A similar rules fix (not a variant) for classes like the Cleric, Paladin, Artificer, and Bard, who have to maintain multiple magic weapons and/or implements to keep pace with other classes. Probably along the lines of inherent bonuses as the Character Builder allows.
3) Monster math adjusted to allow for removal of the Expertise and Defenses feats.
4) Most of the game is 'mechanics with flavor'. Background Benefits and the new Character Themes are 'flavor with mechanics'. I expect that the existing 'flavor with mechanics' will stop being a variant and become part of the expected power curve.
#1 has been mostly fixed by adding more options for the disparate builds, and more 'Strength OR Charisma' powers, as we've been seeing recently. #2 and #3 would just be the canonization of common house rules. #4 I think is significant, given the increase in power that Character Themes grant - the free encounter power is quite significant, especially at level 1, and there's no tradeoff to get it (unless I'm missing something).
I really don't see much more that requires patching, aside from the mounds and mounds of errata to various powers, feats and items. That, however, is largely unavoidable, unless they start pre-releasing everything to all ENWorld subscribers so they can be your Beta testers, Mike.
EDIT: I almost forgot the recent changes to ability scores. I could very well see all races getting the '+2 to this score, and +2 to one of these two' setup. Maybe also making ability score increases to 3 stats rather than 2. Still not enough to justify a system reboot, though.