Not sure to be honest. I've loved Reeves since the Apes movies, which I think are still criminally underrated, but he seems to love exploring grittier themes. Finding hope and optimism through a prism of suffering. I have no doubt he could make a good movie with the Superman story, but would that necessarily be the best choice for Supes?
I also kinda don't want to see Superman or any other JL members connected to this Batverse, if I'm being honest. I love Batman as a character but I always thought his best stories were the ones with the fewest ties to the wider DC universe. I would much rather see them invest and expand on the Batverse, finally do Robin and co. justice.
The reason this movie worked so well is Reeves really nailed that feeling of Gotham being like a prison the citizens are trapped in. It's like a dark swamp and there's no escaping it. Batman is the only source of hope and he's a flawed, dark figure to even provide that properly. To me that illusion breaks a little the more I think about bright and shiny metropolis or other stuff like that.
That said, I DO slightly wish Reeves wasn't so against some of the more fantastical elements of the Batman verse. Like it's a shame that it might mean never getting to see a proper Ivy or Freeze or people like that. That said, I'm definitely hungry for more of this universe and whatever it involves.