Hmmm, interesting. Gearbox is working on that game they announced a while back, Turtle Rock is still doing Evolve stuff, Firaxis is doing Civ:BE expansions (and maybe an XCOM:EW follow up), and I'm 99% positive this isn't Mafia.
So either Novato isn't working on Mafia and is on this, it's a studio that doesn't typically work with 2K, or it's a new 2K studio. My bet would be on Novato having moved to Bioshock after Irrational shut down, and this is that project. Or maybe this is a new IP (but I doubt that).
I'll put out what might sound a bit stupid (since the process flow sounds bonkers to me), but feel Take-Two is crazy enough to have done:
-So we know that Mafia 3 was originally by 2K Prague and was aiming for the PS4/XB1 launch.
-After 2K Prague couldn't get it out the door, the studio was shut down and the game was moved to 2K Novato/Hangar 13 with a similar launch period (or you know, maybe one year in).
-However, I think they may have decided to can the game (the first two did 5 million combined, it likely wasn't going places too), but still had all the game's technology left over, and still needed someone to helm the much more successful BioShock series. It's stated the series would be made by a Marin studio as well, which is where Hangar 13 is located.
-As such, Hangar 13 took the series and turned it into an open world game with all the types of things you'd expect in an open world game (vehicles, missions, etc).