Have Snoke be a possessed darkside worshiper that Palpatine’s spirit took over.
If Palps is supposed to be in Episode 9, then that would be the best way to retcon him as the true villain of the sequel trilogy.
Have him take over Kylo Ren and Ben sacrifices himself to save Rey during the final battle. Palps would not have any dark siders to possess and it would be over.
Leia dies from ongoing sickness/injury from her spacewalk in TLJ at the end of the movie and we end with all of the heroes at her funeral and all of the Jedi’s force ghosts show up to honor her and mark the prophecy as fullfilled. Thus, the Skywalker bloodline is over and we end the saga with a group shot of everyone.