My GTA5 Wishlist
Philadelphia as the next city
Dynamic housing. A lot of people like to be urban explorers. R* should make every building, tunnel, manhole, garage, closet, hangar, etc. fully explorable.
Houses (and apartment complexes) have legal owners & occupants. Killing someone on the street should have repercussions somewhere in the city, small or catastrophic.
Houses should be able to burn down, and enough fire damage to critical parts should be able to 'collapse' the house, in the sense that no one will spawn there. Also fires should be able to spread. Molotov to the NYPD, anyone?
Destructable environment. Make every stairwell, door, wall, ramp, statue, pole, etc. fully destructable.
Certain vehicles (vans, ambulances, helicopters, trains, buses, etc) should be able to exit INSIDE of it. Back doors to vehicles (delivery trucks, etc) should be fully openable.
Get rid of the safehouse parking system. Legally acquired vehicles should have a chance of being stolen (or towed if you fucked up parking) anywhere, but you might always find it again. Of course certain vehicles (Police/FIB/EMS) won't exactly be aquired legally, you'll have to find some place good to park it (like inside a port-district warehouse garage).
BRING IN MACHINE GUNS ALREADY! Pennsylvania (where Philly is btw) made it's fortune on two things, coal and guns. I WANTZ M60E3 I WANTS M280
Also different variations of RPG.
There should be hundreds of guns in GTAV. Do not list stats on them, but make them close enough to their real counterpart in name.
All weapons should have a specific kind of ammo to use, and you should be able to switch between them. Main character should have a certain carrying capacity in Weight and Volume which can be used by ammunition. The AA-12 for example can have 6 different kinds of ammunition, and each of them has a different density. The player can store ammo for guns (all ammo for all guns counts toward the ammo limit) up until either the volume or weight limit has been reached. The player can fit munitions inside of boxes and carry them or crates and load them into a truck/van etc. to transport them, or maybe to set up an arms cache in an unmarked van somewhere in town?
All weapons should use a certain type of ammunition. Different munitions would have different effects, as well as different velocities and mass (remember shell casing has mass too). Multiple weapons should be able to fire the same rounds. For example, Baretta's 92, M1952, 8000, Cx4, 9000, Model 38, Model 3, ans the M12 all use 9x19 Parabellum rounds, as do the MP18 and the infamous H&K MP5. And that's not even 1/5 of the guns firing the notorious 9x19p. I won't even go into shotguns using generic 12gauge rounds.