Seems like you might get your wish! Reeves said in an interview published today that he's not sure if Keoghan will reprise his role as Joker or if the character will appear in later films:

“You’re right,” Reeves says. “It is the Joker.”

While it may seem obvious that Reeves placed this scene at the end of “The Batman” to set up Keoghan as the lead villain for the inevitable sequel, the director was quick to explain that not only was that not his intention, he is in no way convinced that Keoghan’s Joker will appear in any more “Batman” movies.

“It’s not an Easter egg scene,” he says. “It’s not one of those end credits Marvel or DC scenes where it’s going, like, ‘Hey, here’s the next movie!’ In fact, I have no idea when or if we would return to that character in the movies.”

...

Reeves knows that introducing the Joker so close to the end of the movie will invariably lead audiences to expect to see more of him in the next film. But that was not anywhere close to his goal. “I never was trying to say like, ‘Hey, guess what, here’s the Joker. Next movie!'” he says. “The idea was more to say, ‘Hey, look, if you think that trouble is going to go away in Gotham, you can forget it. It’s already here. And it’s already delicious.'”

https://variety.com/2022/film/news/the-batman-ending-joker-barry-keoghan-matt-reeves-1235196812/