The Batman works for any movie that has Batman in it as the lead.
We already had a movie that was simply titled Batman back in 1989, though certainly, they could reuse that if they really wanted to.
It’s not an origin story, so anything even along the same lines as Batman Begins doesn’t work.
Yet, as the first Batman movie within a new DC Universe framework, it would seem that it should get a similarly simple title, something simple along the lines of Wonder Woman or Man of Steel.