Was thinking about a GTA set in 1978 in New York. However, why just stick to one year? Imagine GTA updated yearly. Like the game starts in 1978 but then the last update for the follow-up GTA (GTA 7) finishes the game in 1984.
What would this mean?
So, newer model cars of the same car get added to the game. You could be driving a 1978 Sentinel when you first purchase the game. If you are playing GTA, 5 years later you could be driving the 1983 version of that Sentinel. Is this too ambitious? Seems like a logical step forward in video-game realism.
Seasons could be implemented too. Updates 4 times a year could make little changes to clothes, cars, adverts to reflect time passing by as well as changing foliage, and hours of daylight in a game. Playing GTA in winter will give you extra long nights.
Rockstar could also design missions around the seasons like they do with TV shows. Say HBO make a TV series like The Sopranos. Its most likely shot in the summer. But they sync the show's timeline with real life so you get an episode that references Christmas or Thanksgiving in December. Rockstar, knowing it will be there will be longer, darker nights in winter can have certain ambient missions that only trigger around seasonal times like whacking someone at an ice rink dressed as Santa Clause then disappearing into the busy New York streets where there are a dozen other Santa Clauses. Silly idea, but you get the point.
Building sites actually become finished buildings over time. New graffiti appears on the subways. Rust and permanent wear and tear start to form on the oldest cars you own. Imagine that over time, the pay 'n spray effects start to diminish. After a few years, there are just things that won't get fixed by like rust on your car.
The radio can be updated with songs that reflect the times too.
Could this work? Would it be too ambitious or impossible to pull off?