I'm all on board for it. There has been a few hints throughout the series that suggest it's going to happen. Even Law himself said that one day him and Luffy would become enemies. Given Luffy's nature, he simply wouldn't accept the dissolution of the alliance after Wano as a means for them to become enemies. Law would have to do something that really pisses Luffy off to get him to view him as one.
And I know a lot of people counter argue that Law owes Luffy for the Doflamingo thing, but I think they forget that Luffy owed Law first because he saved his life. So if Oda really wanted to make Law betray Luffy, then that could serve as a means to make them even in Laws mind.