In an interview with Josh Horowitz, the elusive leading man/perpetual art project James Franco let slip some details about his role in the eagerly-anticipated sequel to "Rise of the Planet of the Apes." He said:
I was going to be a small part of the next one. There was a moment when Rupert Wyatt was going to direct the second one. A lot of the human characters that were in the first movie were dead in the sequel that Rupert was going to direct. But there was one scene, between Caesar and my character, maybe even just like on a video that was left behind, but then a lot of things happened, like [former Fox co-chairman] Tom Rothman who was a big part of the first movie, left. Now Rupert's not a part of it so I don't know. My guess is I won't be in it. Nobody's talked to me since Rupert left.
While promoting "The Hobbit," the real star of "Rise," Andy Serkis, who played rising ape Ceaser told Coming Soon:
The interesting thing now will be how Caesar operates in this world--because of the virus that hits at the end of the first movie--and how Caesar brings an accord between the apes and the surviving humans and that's going to be interesting where we take that.
So putting two and two together, we can assume that Franco's scientist cum genius-ape owner isn't necessarily needed for a story that will take place in what essentially will be a post-apocalypic (for humanity) but newly forming Ape-run world. So maybe Franco will just cameo like he says above, or maybe we'll get the movie that we all want to see anyway - one that forgoes the pesky humans in favor of ruthless yet brainy ape-on-ape action.