You’re wrong about the lightsaber, although I’m not sure how much it undermines the theory, given that there is much we don’t know still. The lightsaber Rey gets is not the one Obi-Wan gave Luke; that lightsaber (Anakin’s) was lost during the Cloud City duel, along with Luke’s hand. Luke built a new, green-bladed one in between Empire and Jedi. Unless somehow Anakin Skywalker’s blue-bladed lightsaber was retrieved, that one, and its connection to Obi-Wan, is gone.

I would like for Rey’s lightsaber to have belonged to Ben Solo, and for Luke to have saved it, hidden away, once Ben became Kylo Ren. That would explain more of Rey’s vision, and make a nice narrative parallel: masters saving their corrupted padawans’ original weapons, which are then passed on to the next hero.