So, Ubisoft revealed their future plans for assassin's creed franchise.
Assassin's creed mirage is the Last one which will be like the old Assassin's creed style, it won't be an RPG more like a linear action game.
It was originally supposed to be a DLC for Valhalla but they made it into a standalone game, that's also why it will be a smaller game with only one city (Baghdad) and a smaller map.
Assassin's Creed Mirage Official Reveal Trailer | Ubisoft Forward 2022 - YouTube
Summary of Ubisoft forward:
1: Valhalla DLC
2: Assassin's creed mirage