Dragonblade
Adventurer
Its easy to see how that list would appeal to existing 4E fans. But, the exception here or there aside, the things that alienate a large portion of the fan base from 4E would continue to alienate that same portion from this hypothetical 5E.
Which isn't to say that making it 3E light wouldn't alienate 4E fans now. You can't put that genie back either.
My own group includes some 4e diehards and some Pathfinder diehards. After playing both extensively, we have come to a consensus that there are aspects of both systems we like and aspects we don't. Those are pretty much laid out in my first post.
After cutting through all the edition war BS even in our group, what it really came down to for the Pathfinder guys is that most 4e changes aren't an issue. Its the fact that so much of the feel of 4e comes from the cookie cutter classes/powers/magic items. And that boardgame/gamist atmosphere is what they hate the most. And of course that is huge. It defines the whole game after all.
For the 4e guys their biggest frustration was going back to things like failing a save and sitting out of the rest of combat, or going back to the 15 minute adventuring day because magic and so many classes powers are tied to a daily refresh. Random HP, and the fiddly and annoying combat rules like excitedly rolling a natural 20, only to see it lost after failing the confirmation roll.
But after talking it over, if you could keep Pathfinder style classes and magic, but bring in the 4e elements that do work and actually did make the game better, then you could have a truly evolved and fun system that would appeal to everyone.

Well, almost everyone.
