You can scale up the threat or make it a different threat without tearing apart the existing characters. Keep Luke powerful and consistent, but make him go up against something that matches him in power or tests him in a way he hasn’t dealt with before (no, this does not include a family member going to the dark side.) Killing Han and Leia’s marriage for no reason is not productive and has no effect on the story either way, other than to satisfy bitter people who don’t think happy marriages exist or should exist. If the new Jedi were like they were in the EU it would be a lot better, so I have no complaints there.

I made a thread about this but I think the Cobra Kai show is a great model of how you would do it. The original characters are respected but still have drama and face new problems all the time. Some original characters that were more minor are thoroughly fleshed out and turned into main characters. The new characters are developed through constant direct interactions with the original characters, and the audience cares about them because of those strong relationships.