I submit that Kylo Ren possessing Vader’s charred helmet is evidence of the resurrection of Darth Plagueis in the body of Vader. Someone saved the helmet from the fire and I believe it’s more likely that the helmet was carried from the fire by Vader than it is that someone stole only the helmet from a burning corpse in the middle of the night after Luke left his burning body. I don’t care what Disney says about Snoke not being Plagueis, it could just be misdirection to preserve their massive reveal.
What do you think of this theory? I think it has some problems, but I do think there are many unanswered questions left from the Prequels that leave the opportunity open for Plagueis to return and take credit for, if nothing else, the creation of Anakin Skywalker.