I actually hope it's the opposite.
Tired of this Shanks being Luffy's hero and gatekeeper shit.
Shanks being the villain would be one of the most interesting twists ever.
While i like the twist as an idea, i wouldn't care for it realized.
It would feel like a "Star Wars The Last Jedi Subversion"-type twist for me, a forced change on the narrative so far just to be a surprise, because Shanks simply defeating Teach and the story being over with Blackbeard would be the most disappointing shit ever.
It would be like the death of the Night King on GoT, when people were just asking to each other "that's it?" about Blackbeard once he got beaten.
I think a lot of people underestimate the role Blackbeard will play on the last few arcs, even if the Marines and World Governament are the big antagonists of the world. The Blackbeard Pirates is the only crew we have been following for a long time and seing them improve little by little, with Teach always one upping Luffy every arc.
So if Luffy is taking down Kaido and / or Big Mom in Wano, Blackbeard will have to do some big shit out there at the same time, either taking on Shanks or finding an Ancient Weapon.