I think JoyBoy was able to use the same kind of thing Imu could do but instead of turning other people into demons Joyboy was able to turn them "white" and give them cartoon powers.

I think we'll see another Nikafied character soon and I'm betting it'll be Usopp. Usopp with Nika powers would be more on par with a character being One Piece's "the mask" than Luffy would be.
Overall I think picrel will happen at least during the final fight of the series.
But please don't be afraid to call me schizophrenic and retarded.