It would be a totally revamped movie. I think an earlier title was "Batman Continues" so let's assume it's that.
My POD would be that the writer for Batman Returns gets earlier feedback that it is too dark and lightens it to the levels of the 1989 movie. The backlash was only recognized at the first screening. By then it was too late. Burton, initially hesitant to do a second Batman film, was all for a third one in the OTL but the studio pressured him out of it. Here, he could still be on board because of a lack of popular backlash.
Burton's Batman 3 has a number of possibilities. For one, Marlon Wayans was originally tapped to be Robin. He was bought out of his contract in the OTL when Schumacher took over, and still receives royalty checks. Thirdly, either Robin Williams or Micky Dolenz were tapped to be the Riddler. Williams may not be part of it since he was burned in the OTL. He was used as a negotiating ploy to get Jack Nicholson to be the Joker. Billy Dee Williams was tapped to be Two-Face at some point, though it may not be in the third film. And Catwoman was supposed to be part of the franchise as it went on.
The series was project to last for 4 films. My money is that you'd have Robin introduced in the third one, have Riddler as the main film villain, and have Two-Face introduced in the third to be carried over to the fourth film. Keaton also really wanted to cover and explore the Bruce Wayne character in depth, like Nolan did, and may have gotten Burton to do that for the third and fourth films. And the thing people forget is Keaton didn't give up on Batman Forever because Burton wasn't directing. He thought Schumacher's script and direction sucked for the third one. He would have stayed on had it remained the same Batman under another director.