I think Ben needs to survive. He feels really out of place as a force ghost, and the movie makes it clear that Leia only stopped training because her son would die if she continued.
Except he still died, so what was the point of her not being a Jedi?!?
Ben dying makes Leia’s storyline even worse in TRoS. Cut his death.
I like that, conceptually, but then it becomes awkward that he doesn’t leave Exegol, or have any end scene somewhere (Ajan Kloss or elsewhere). This is part of what made cutting Lando and Jannah’s scene outright difficult, because it’s the only footage of them on Ajan Kloss for the celebrations. You would still need to insert him to either that scene or on Tatooine, or create a new scene of him somewhere else alone.