Maybe a game that is set to Vice City and Florida would be interesting. Miami is such a huge city, and its further urbanization really changed it from the 1980's skyline. From the beaches to the Everglades national park, I think it could match, if not improve on the ideas that were applied in GTA V.
However, I think character design and the story should be less like the one from GTA V, but something closer to San Andreas, but building around improving the experience of playing as CJ. (Someone who came back home, only to be met with death of friends, and relatives and built their way up)
Perhaps, an ex-convict who in their teens were put in jail for drug trafficking or some other sentence and they are released out of prison, whilst trying to find their old friends, establish connections, meeting relatives and struggling between a restrained personality and a full-blown psychopath that the player has control over.