This is quite clearly all BS, but if you disregard that and just read it as if its one guys wish list, its pretty good. although it's a long read.
I especially like the part about how there could be models of the cars from all the different GTA eras, as with real life where you expect to see new and old cars, you could see a Perennial as it looked in Vice City from 1986, and as it looked in GTA IV in 2008. That would be awesome in my opinion.
His talk about the size of the map would be pretty sweet too.