Ngl I definitely do miss having that Palpatine line because of everything it alludes to. Influence the midichlorians to create life (Force-sensitive clones), cheating death (essence transfer).
The problem is that I also like Kylo knowing that it’s a bad idea to kill Palpatine. That threat of the power he has to possess him should be what stops Kylo from killing him.
Could the lines be swapped?
To Kylo: “I have died before. Kill me and my spirit will pass into you, as all the Sith live in me.”
To Rey: “You want to kill me, that is what I want. The dark side of the Force is a pathway to many abilities some consider to be unnatural. You will be Empress. We will be one.”