The speculation and chatter online about who will be the DCU's Batman has been a topic of much discussion. Despite the announcement made three years ago that the DCU's Dark Knight would be a different iteration of the character and played by a new actor, some fans have persisted in their belief that Robert Pattinson's Bruce Wayne from Matt Reeves' The Batman would somehow be grandfathered in. However, DC co-head James Gunn has consistently stated that this is not going to happen. Now, he has been definitive about it. According to Den of Geek, when a fan asked Gunn on Threads if there was any chance of Battinson joining the DCU, Gunn bluntly said "No."
So, that's it folks. The DCU Batman will 100% not be the Caped Crusader who eventually meets David Corenswet's Superman or Nicholas Hoult's Lex Luthor. It will be someone else wearing the cape and cowl. So please, for the love of Gotham, stop asking James Gunn about it on social media.

In the meantime, Robert Pattinson will continue to play the character in The Batman - Part II, and if all goes well, probably a Part III at some point. We are nowhere near done with Matt Reeves' realistic take on the Batman mythos.
As for who is playing the DCU Batman, we have a suspicion that the announcement is not coming anytime soon. They only recently announced that Batman: The Brave and the Bold was getting a new screenwriter. So we're still a long way away from production starting. Unless the new DCU Batman has a cameo in Man of Tomorrow, of course. Then we might get a casting announcement ahead of Brave and the Bold. But James Gunn has downplayed the idea that either Wonder Woman or Batman is appearing in the next Superman adventure. So we wouldn't hold our breath. But it'll happen one day. There's a name actor out there right now, just waiting for the Bat-signal to light up and answer the call.