^I don't really see the Marlon Wayan's/ Nicolas Cage cameos being anything that would generate buzz, as those were never actually seen/ or even known about by the majority of the general public, that would just be an inside joke for fans
if you going to take the route of people who "almost" played a role, what about bringing back anyone for JL: Mortals?
an personally anything from the Nolanverse wouldn't do much for me, they completed their story arc (even if I didn't agree with the direction it took)... an I didn't really care for the whole John "Robin" Blake thing enough to want to see him as the next Bats/Nightwing/ or whatever he ended up becoming
there was some neat fan speculation at the time of what could have been/ or what he did after... but, it doesn't need to be explored
it's different then bringing Keaton back, as he never got a chance to complete his Bat story, and it was long enough ago for it to be a nostalgia thing to see him again in the role ... Nolanverse was only in the last 10-15 years
As I said, this is my own personal opinion that I would like to see. We can agree to disagree.
At the risk of upsetting some Snyder fans, the Flashpoint idea could offer them the opportunity to soft reboot, ignore the existence of BvS/JL and then pick and choose what elements and history they want to keep going forward.
This is obviously complicated by the release of Zack Snyder’s Justice League which, if successful, I’d expect HBOMax would want to continue. What would then come from that I’m not sure? Just JL 2&3 to complete his 5 part arc? Would Ben Affleck want to come back?
These are questions that will be answered going forward but if we hypothetically assume the Snyder cut is just a one-off that closes that chapter, you could end the Flashpoint movie creating a new DCEU timeline.
When the Flash resets the timeline and comes back to present day, Michael Keaton could be the Batman of the DCEU who has just retired from the Justice League and is about to pass the baton to Batgirl or Nightwing. You could then show Barry contacting Henry Cavill where it could pick up after Man of Steel or just Henry as Clark Kent who is working at the Daily Planet and we don’t know his history. Wonder Woman 3 could take place in the new present day timeline and her history remains the same (WW + WW1984).
I like this, a lot and is something I have been saying all along and I believe a few more have hinted it could reset things.
I like the idea that Eobard Thawne - way back in the 30's was a college professor where a certain J Garrick entailed water vapours and had a flash of luck.... so to speak, becoming the first flash - which, was an extremely low key situation... more on that later.
He recreates the formula for himself, and is able temporarily mimic the flash in all things, but it being temporary, it's weaker... and he has less control - he is able to tap into the speed force - but he can't control it - he isn't able to return to the point he left, like Jay... thus, creating the multiverse, new time lines, fracturing time... up until then, there was only ever one time line, a universal rule as it has been messed with before. Filled with rage and wanting to go back, he tries and tried and failed, being lost int he speed force, watching from the outside of all these realities he has created... the tragic part is he has no concept of time... so he sees the creation and the destruction of universes... what he has also pondered is that each universe he created, the flash of each is unique and weaker in some aspects - no-one will probably be prime flash... no villain will be worthy, but it was too late as he is stuck. He has has had brushes with other versions of himself... but nothing is good enough to fix or control his mistake and the rage - it manifested him.
Until.... Barry Allen of the DCEU pops up. battle ensue, resulting in the multiverse converging to form one... where the energies of it all go to one prime universe and earth.
Which gives us the DCEU proper - which leaves the WW solos intact, MOS intact, Batman was around in the 80's/90's and at this point is now retired, with the bat family taken charge of Gotham.
SS never happened, BvS, JL, never happened...
Shazam! retconned so that the events of BvS and JL never happened,..
SS reboot happens, but, we have no mention of the bat family... because, well... it's easier that way.
Moving forward, Keaton leads the group.. when necessary... superman is the prime hero along with WW. Batgirl is the bat representitive..
We see more MOS sequels, we see bat family movies and Shazam! more AM, SS moving forward can involve the bat family...
Easy...