I don't get how people still think that the theory of Blackbeard killing Shanks which is as old as MF is happening when Oda always does his best to be unpredictable, like, he kills off Shanks off-screen in a random encounter with Teach ?
If Teach and Shanks were to meet now it wouldn't end well for Teach. Best bet is Luffy defeating Shanks and both together face an OP Blackbeard.