If Michael Keaton didn't want to return, would you be okay with a recasting?
Say in the future they decide to introduce the Sinister Six, meaning the return of the Vulture... Now, Michael Keaton was only signed for one movie... So, he's not obligated to return to the role...
So, if they were going to use the Vulture again, but Michael Keaton decided he didn't want to return to the role for some reason, would you be okay if they recast the role and referred to the character as Blackie Drago, the second Vulture?
I don't see why Michael Keaton wouldn't want to return, but just in case, they could always introduce another character taking over the wings.