Shanks vs Blackbeard is literally the most consistently pushed subplot in the manga. It’s been set up since Water 7 when Shanks specifically met with another yonko to discuss Blackbeard and mentioned that his scar was given to him by Blackbeard and still hurts.
Then we see Shanks making moves in the New World, and what’s the first move we’re fully told about? He shows up outside of Wano expecting Blackbeard to show up. When Blackbeard doesn’t, he continues his hunt and heads to one of the islands following Blackbeard and goes to Elbaf.
You can continue pushing that Shanks vs Blackbeard is only going to happen during some over bloated Battle Royale that has never been odas style before, or you can accept that yes Blackbeard and Shanks will fight in the near future.