I'm willing to bet Kid is going to cheapshot him, like Mr. Go did to Luffy, so that Blackbeard can get the lethal hit. Like probably assign Shanks's sword to the ground while he's focused on Teach.
Kid has significant build up with shanks and Oda needs to have him do something to justify him getting the 5 billion+ bounty alongside Luffy.
Also, Teach full on mid diffing shanks would be absolutely bonkers and would turn Luffy vs Blackbeard into another asspull fight like Luffy vs kaido.