User blog comment:ScorpioTheBadGuy/Speculating The Season 6 Returnees Of Total Drama/@comment-4393544-20150819094811

My theories

Island vets: Harold, Leshawna (but they'll be early fodder in favor of PI contestants) and Cody (but only if Gwen and Cameron are contestants again)

ROTI vets: Brick, Dawn and B (but they too, will be fodder)

PI vets: Dave, Sky, Shawn, Jasmine (probably an early out) Max, Samey (probably the final two) Amy and Sugar

RR vets: Kitty (has the best chance of being in seasons of Total Drama in my view)