>Team RR is not dismantled at the end of RR episode
>Giovanni can still apparently warp into alternate dimensions
>Still has Mega Mewtwo
>"Now, what new world shall I unleash my evil schemes upon"
There's no way this guy isn't coming back.
What do you think he'll do next in future games ? (Depending on what game you think will happen : Gen VIII obviously, remakes, other)
Reuniting all bosses was already a pretty big deal, what could be worse than that ?