8. One Single Game Universe
Rockstar have hinted at this in the past through
easter eggs and the like, but they're yet to tie the older events of the games into the new universe officially. By having guys like Tommy Vercetti, CJ, hell even Claude as mission givers or influential figures in the various cities and conversations you'll have would build the GTA brand immensely, instead of this weird Final Fantasy-esque "each one is completely different but similar" shtick. People loved when GTA III's Claude turned up in San Andreas, and the possibilities are pretty endless now that Rockstar have created five entire worlds of characters to then mash together - it's just a case of doing so in the most entertaining way.