While Spider-Man: Brand New Day will serve as a fresh start for the Spider-Man movie franchise, as Tom Holland said during the CinemaCon title reveal, Zendaya's MJ will reportedly appear in a minor role. Based on the comics the MCU movie takes inspiration from, I think her return in a smaller role makes sense. In the comics, Mary Jane Watson was dating movie star Bobby Carr when she returned during the "Brand New Day" arc. I think we could see Peter checking up on her, only to find out Zendaya's MJ is happy with a new boyfriend.