I have no doubt that a small subset of the viewing audience would be morbidly curious enough to see
Flash in theatres. But I refuse to believe that the vast majority of moviegoers - at least the ones with any kind of decent moral compass - would be willing to support this film with their hard-earned dollars. I have to cling to some belief in the goodness of humanity after all...
I agree that the studio's safest bet at this point would be to dump
Flash on HBO Max. Make it a Holiday exclusive with limited promotion, assign the production costs to their streaming content budget, and write-off the rest towards their theatrical unit. However, as
@kguillou pointed out, there are tons of other fiscal considerations to worry about. There are undoubtedly countless corporate partnerships, product tie-ins, media contracts, participation agreements for the cast & crew...all the flotsam and jetsam typical of big-budget filmmaking to consider. And that doesn't even include all the ancillary sources of income that will be lost - VOD, streaming, physical/digital releases, etc. Undoubtedly there are tens of millions of dollars in pre-signed contracts that will have to be made null & void...
Thing is, unless Miller had a profit percentage of the movie in their contract, they've already made their money from the performance. Not seeing the movie wouldn't prevent them from earning, in that case. Perhaps there are royalties from home video sales and such... but if I were WB I'd donate those proceeds to mental health awareness/sexual assault victim charities, if they could find a way to legally void those areas of Miller's contract. Also, scrap all merch for the movie that features Flash himself, or scrap the likeness to Miller from it all, that way Ezra doesn't get likeness royalties.
I've been thinking about it a lot in the last couple of days and my stance has changed, slightly. I think that with a public-enough firing of Miller, along with heavily promoting said donations could help offset (not eliminate) the controversy of the movie. You certainly couldn't release the movie untouched if it seemed like Miller wasn't facing consequences, but once fired it becomes a little more doable, as any talk of Miller from the studio can be aligned with the public opinion. Of course, I still think you need to re-shoot the ending to make clear they're replaced by the end.
It wouldn't be a perfect solution, but in all honesty the public at large isn't as aware of this stuff as most of us on the internet think. This hasn't been reported widely enough yet (though it would be once promotion started up), as for right now, you sort-of have to be traveling in geek communities on the 'net to really know all the gory details. If WB jumped on controlling the wider narrative early (that Miller's actions are fully condemned by WB and they want to spread awareness of such problems/people), then that would actually probably be enough for most people.
You know, combined with what we've said before about pushing the stuff in the movie that people actually WANT to see--Keaton being chief among them. Sure, the profit's gonna take a hit either way, but in a world where someone like Trump can get elected, don't put much faith in people's desire to pay enough attention or spend the energy on moral outrage. I think that's probably the best way to take the bath on the movie while minimizing the losses. It's gonna take a hit, no matter what... but it's potentially less of a hit this way than either shelving the movie or replacing Miller in the footage.
EDIT: Even more, as part of controlling the narrative, I could see WB filming a promo with Keaton that plays before every showing of the movie, talking about WB's donations and what to do if you've been groomed/assaulted (make it classier by not specifically mentioning Miller by name), and have Keaton say something like "in spite of the controversy, this film employed thousands of people and brought jobs (etc), and we wanted to honor the work these artisans put in by releasing their work to the world", and pan back to show the entire crew shouting "thank you" or something.
That would be quite the attempt at a moral power move by WB