At the end of the day, the 2024 book will be nothing more than a book of alternate and/or additional rules, no different than Xanathar's and Tasha's. And some people will adopt them, others won't.
If there's any semblance of a "split"... it'll just be the same as it always is: a few people who don't like some of the alternate and/or additional rules will come here on the boards saying the rules are terrible, the game has been destroyed, the designers are lazy/stupid for creating what they did, and that they are going to have to leave the game now because D&D has left them behind, whoa is me.
No different than what happens after every single player-facing book gets released.