>>96239956
Even if Nasu decides to not continue FGO's story further I'm sure the game will continue existing for a while purely because of how much of a cash cow it is.

On the other hand, Nasu has already stated he likes the feeling of tuning in for limited content like watching anime on tv and that's why most side events aren't playable after they end, so it would be super funny if he just immediately cut off FGO when the story ended. Unfortunately, he probably doesn't have the executive power to do so though.