Many things over time, but right now I am building a huge island in max with a mansion in the middle and a race track going around the outside. I will have all of my modded cars parked up outside the mansion, but say I wanted to create another racetrack across town and want to use different custom cars but with replacing the same original vehicle, as I get closer the old custom cars will turn off and new ones will turn on.
Same with handling lines, weapons, replaced models, maps ect ect. It'll be good to switch switch between them based on your location, or even other things like time or weather, the possibilities are endless.
Oh and another this I will do is trigger traffic to spawn and go around the track when I get close enough. 36 AI high poly custom cars endlessly driving around at the other side of map when no one is near is just a waste of cpu.
And plus where I have all of my custom cars together when I am far and facing that direction it causes a lot of lag, so I would like them not to load until I am closer so can have less cars on the screen, I know that sounds :~ but if you place the vehicles right you wont see them change.