GTA 6: 10 Killer Features That Would Make It Great
1. A Time Lapse Moment
It's always admirable when game designers try to insert one of those time lapse tropes. Battlefield: Hardline and Wolfenstein: The New Order are both examples of this, though it is true they had varying success (Wolfenstein more than Battlefield captured the strangeness of years passing in an instant).
GTA 6, and Rockstar in general, should give it a go.
Picture the scene: the chief protagonist is jailed for 10/20 years, either rightfully or wrongfully, and forced to adapt to a changed world upon being set free. That comes with problems, and it'd be almost like the character had been released from stasis; still living in the past, they'd struggle to acclimatise themselves to the present.
This would allow Rockstar to use a Vice City players are more familiar with from the late-80s/early-90s and then use a present day setting in the same story. That'd be a thrill ride, one the developers are likely to handle with care and would also let them pen a daring prison escape sequence.