Ok so here goes. I work in the game industry and I learned this from a guy who work in a Sony studio (in a private chat room). Can't tell more.
Some details:
-The game will be divided into 2 timelines; a retro 70-80's vice city and a modern era vice city inspired from Refn's filmography (Driver, Pusher,etc.)
-2 playable characters (well, no it's the same guy but at the 2 different era). Basically the hero will recall flashbacks that happened in his youth allowing us to play both era
-Of course its 1 map, 1 city but with differences and variations according to the specific time
Which means 2 maps, 2 sets of cars, weapons, styling, clothing, NPC social behaviour, slang,etc.
-More interesting:
Actions done in the past flashbacks will impact the modern era of the game (both storyline and side missions).
Synthwave and City Pop will both be the defining soundtrack of the game.
Discuss.
Be mindful those are early discussions, the game is still in heavy development and a lot of those ideas might completely be omitted from the released materials.