Since all of the news seems to be about the upcoming D&D 5e, I figured I'd make a list of what would be in my personal "perfect" edition:
1. Ascending AC.
2. Reflex, Fortitude, and Will Saves.
3. Fighter, Mage, Rogue, and Cleric.
4. Options to modify the base classes:
4a: Fighters have options to gain cleric spells or mage spells, fight with light armor and rapiers, etc.
4b: Mages specialize like they did in 2e. They can also gain special abilities based upon spec, so that necromancers can raise weak undead at level 1, witch doctors can use some healing spells, etc.
4c: Clerics have Domains like 3e, and gain weapon use based upon their god. Not all Turn Undead, instead maybe having stuff like Thief clerics gaining thief abilities or Nature clerics basically being Druids.
4d: Rogues would have options to become bards, burglars, assassins, or monks.
5. Races included would be: human, elf, dwarf, halfling, gnome, shifter, dragonborn, tiefling, and aasimar.
6. High level options including a decent rulership system and maybe a mass combat system (though I'm not really sold on the necessity of this).
7. Vancian magic, because I like it.
- There's probably other stuff I'm not thinking of right now, but these would all be awesome as a base starting point.