Things like the Return of The Joker flashbacks could be retrofitted for a Damian Batman future. It also allows a larger gap between now and that future so that way you can have a more immediate future akin to what we see in the second Rebirth Batman annual or a more positive version of the story Tim Drake of Tomorrow told in Detective Comics #966.
I like this theory
Maybe have Damian become the new Ra’s Al Ghul, making him a villain in the movie.
He is that way in Rebirth, but he still becomes a hero after reconciling with Bruce. I think he tried to wear a prototype B. Beyond suit that drove him a little crazy.
The bigger time gap could also get rid of a lot of the messed up ‘future’ drama with current beloved characters… I would support that.
It could at least work.