So the final villain of this manga is just a born human who ate a devil fruit? Nah bro. The final villain of this manga is a primordial godlike entity that enslaved humanity, not a fucking girl who ate a devil fruit lol.
If Imu is a Celestial Dragon possessed by a Demonic entity, I'd much prefer Teach to be the final boss.
Honestly, I've really come around to the idea of Teach losing out on Laugh Tale, but continuing on, anyway.
Luffy lost bad in Marineford, then came back to pick up the pieces.
I could see Oda doing a "Teach found part of the treasure, but not the whole One Piece"
Luffy beats Teach in Laugh Tale, then allies with him to defeat Imu. Right after defeating Imu, Teach betrays Luffy, and uses his Fruit to gain Imu's powers.
There's so many interesting places Oda can take this, I really feel Teach needs to be in the final fight on some level.