I hope it won't be VX - VX Ace all over again. I won't buy it, if it's just updated MV.
1. Widescreen resolution support,
2. 64x64 tile or back to 32x32 - 48x48 a was mistake (They already said all sprites from MV will work in MZ which is sad, cuz it means 48x48 again...)
3. In program plugin editor,
4. More event commands - like "Stop Every/Event Movement". It would help a lot with custom event menus etc,
5. Pixel Movement.
6. More self switches,
7. self variables.
8. More control over event speed.
9. XP layers system - with 3 map layers and at least 3 stars layers.
This is what we need. And these are just a few things I wrote quickly from my head.