[Suzu]

Technichally, Tennoji was the final boss of the show, because he was pretty much the only actual "villain" left.

Anyway, I do not believe that Chase will return to being an enemy soon. Unlike Hajime, he is in total control of his powers and was a good guy in the first place, when he war Proto-Drive. So no, I don't think he will be the final boss either. Atm, my bets are on either Banno or maybe even Krim- depends on how the movie works with the show.