Why dont you guys have the community create new textures. Instead of the probably 256 ones ingame now, im sure (myself included) would be happy to recreate the textures but in 1024 or greater. Could the game engine handle higher textures on everything rather than just the stuff you guys have currently done. Like signs and adverts.
Would be interesting to see all environment textures as 2015 quality hehe.
Also character, vehicle and weapon textures could be redone in a jiffy. Use us...we are your best resource.