Affleck himself has suggested that his days as Batman might be numbered, and it’s not like Reeves saying that Affleck would be reprising his role would actually be news WB would want to keep under wraps, so it certainly does sound like there’s a possibility that somebody else could play Batman here.
But with that being the case, you’d expect Ben Affleck to be in it as he is the current DC universe Batman.
Matt Reeves does say that he’s still speaking with Affleck, but he’s clearly stopping short of making a statement on the man’s participation as an actor one way or another.