There's already a draft of the script for the next Tron movie and two of the film's producers, Edward Kitsis and Adam Horowitz, who were writers on Legacy, have read it. They probably shouldn't be saying anything, and indeed they're trying not to.
But you know how it goes. It's hard to keep a secret. It's fun to tease.
Kitsis and Horowitz were addressing a roundtable in respect of Once Upon a Time, the successful ABC series that made them so busy they handed Tron 3 script duties over to Dave DiGilio. Here are the Tronny bits, as shared by io9:
In your opinion are Tron and Jeff Bridges dead, are they in Tron ?
Horowitz: I would say the definition of life and death in the digital realm…
Kitsis: Will be explored in the sequel!
How big of a part does Quorra have in the sequel?
Horrowitz: Mmm. *Darts away to the next roundtable*
If only that first question was about the character Flynn only and not Tron. As it refers to both it's gone from being a potential vague indicator to an extremely vague indicator of Flynn's status. But will Flynn be back even though he died in the last film? I'd certainly be happy to see him – though I hope it's actually him and not another CG puppet.
As for Tron himself, I'm pretty sure he will be back in some shape or form – the film will bear his name after all.
Bruce Boxleitner seems pretty confident that he'll be back, even if only in the fleshy guise of Alan Bradley. A recent I Am Rogue story came with this quote from Boxleitner:
Anything could happen, but all I can say is, it's in its formative stages. Kosinski, who is slated for it, he's shooting another movie now, and then they'll get around to doing that. I think somewhere around 2014, maybe. I'm talking way out of school here, but they can't shoot me because I'm Tron
I'm half expecting Disney to trashcan the film before production starts, but perhaps the budget will be kept reasonable enough and that half of me will be surprised.