What?
We're talking superhero movies here.
I highly doubt Emma Stone would be dropped off a bridge by a dude riding a glider or that Henry Cavill would fight some rock looking monster to the death in Kansas.
If the movie is called MOS: Doomsday and the surprise is Supes dies and the movie is already shot they're not changing how Superman dies. Of course the studio has to handle how the death with care but you don't compromise the movie by changing critical points of the movie. This isn't like when Heath died and it was as simple as not having the Joker in sequels. It's Superman. They wouldn't stop making those movies according to schedule or reboot right after. Choice would be cast somebody new or keep Supes dead for a while until they scrap this shared universe.
That's obviously a different situation for obvious reasons.
There are so many characters in there I don't see working on the big screen.