in fact nothing has been confirmed yet.
According to some sources, there is an issue: it seems like Ben Affleck has a contract, so if he is not directing it, he has to be a part of it somehow, but Reeves would not want him while Warner would like to keep Batfleck.
Some sources say it's because Reeves wants a younger Batman, while others say it's because he does not want any link to Batman v Superman or Justice League (not because of the story, but because of the bad buzz).
This movie actually sounds like a mess already, thanks to Warner (again).
And the last time I heard about Flashpoint, it was because it was impossible to make it easy enough for viewers to understand. Besides, as Warner is not ready to put heroes as villains (especially Aquaman and Wonder Woman, who are at the center of Flashpoint) they were talking about the Rogues... I would rather have no Flashpoint than a ****** Flashpoint
Would have been easier to let Snyder work and do his thing (it was supposed to be 5 movies, the last one being Justice League part 2). They were so scared to bad reviews that they butchered the movies, leading to bad reviews.