I think this is separate from the Star Wars FPS that Respawn was announced to be working on, Henderson is saying this Mandalorian game is early development and Respawn was announced to be making the Star Wars FPS 2 years ago. Also the Star Wars FPS was announced as being directed by Peter Hirschmann, while Grubb said this Mandalorian game was being directed by Mohammad Alavi originally but that he recently left Respawn, so the game would have a new director now. Unless the Star Wars FPS has gone through 3 directors in 2 years, this should be a different game from the FPS announced 2 years ago.
So, this would mean we have 4 Star Wars games in development at Respawn now. Jedi #3, FPS (possibly multiplayer to replace the aging EA Battlefront 2), Mandalorian, and the strategy game in collaboration with Bit Reactor.
