Honestly I am uncertain how Oda will handle Blackbeard but given how OP Imu is I don’t think it makes sense for BB to be suddenly become powerful and kill Imu .
Harley text even indicates sludgy fighting the devil so I don’t think it’s BB he will fight before they enter Laugh tale and BB will lose .
From the North, Akainu, splitting and melting the earth as he walks
From the South, Imu, dragging the raging sea behind her
From the East, Blackbeard, rending the ground and consuming the entire environment in darkness
From the West, Luffy, flying happily while transforming the landscape into a black and white cartoon paradise
All heading towards the center of the island, a massive stone block with a sword standing in the middle, with a tattered red and gold captain’s jacket tied to its hilt fluttering in the wind, and a giant egg with a single crack on the side that begins to break open to the sound of Nika’s heartbeat.
That’s how he will be handled. Blackbeard will go out like an absolute Chad smashing a giant raid boss Luffy with void-earthquake nukes while Luffy breaks the fourth wall and warps reality