Just my 2 cents.
1. NTEC seems a little too good. Though I don't like ttk extensions, short ttk is one of the main apb attractions for me, so maybe just (even) less accuracy. At least make sure it isn't better than everything else.
2. I hate bunny hopping. Make people put away their guns to jump high or something. It's such a stupid, immersion breaking mechanic.
3. I'd like to see the lore of APB worked out further in some PvE stuff. Hell I'd like to see alot of GTA like mechanics added with the customizability of APB to make it more of a criminal world where the pvp is a central pillar of the game, just not the only pillar.
4. Let us buy (lots more) inventory slots for everything. APB's customizability, another fundamental characteristic, should not be limited by something as banal as slots.
5. More destructability.
6. Building interiors, subways. Perhaps merge the district maps so that player pool is bigger and matchmaking is easier.
7. Faster vehicles, make vehicles better in general but make it possible to shoot ppl in vehicles.
8. New vehicle types: motorcycles, helicopters (though not massively weaponized ones like in GTA), boats
9. Traversal: swimming, base jumping, absailing off buildings, climb almost anything, though slowly,
10. Animations: more (configurable) idle animations. Possibly make it possble to choose between different types of weapon reload anims
I guess I could go on for ages. I've always felt that APB had oodles of untapped potential. I've been playing alot more since the 64-bit update and even now I still find the game impressive, the customizations system most of all. Sure, it could use some updates. to textures and 3D, maybe use some more polygons here and there. But, in basis the game, particularly the customization system still impresses me and I struggle to think of another game that allows such massive freedom through a relatively simple interface.
Anyhoo, I hope apb has a bright future post 64 bit update.