While promoting his latest film (Pain & Gain), Michael Bay (who is producing TMNT, not directing it) was asked by moviefone about the alien rumors surrounding TMNT's reboot. He previously made a remark about extraterrestrials, and while everyone jumped to conclusions this meant a planet full of alien Turtles (understandable so, of course), Bay says that's entirely false.
"There was that quote saying that we’re making [the Ninja Turtles as] aliens. We’re not. It’s the ooze! It’s from the original source material. These are from the original writers, and I never went out to correct myself in the press. I do listen to the fans and I do want this to be authentic. I think they’re going to be really happy with this movie. When I see the digital stuff, the turtles look great."
This is what I speculated a long time ago, people! The ooze is technically alien, so I was really, really, reaaaaally hoping he just chose his words poorly, implying they're mutated by alien technology, therefore being part alien. Thankfully, it looks like that's exactly the case and, as far as we can tell, their origin will be heavily inspired by Kevin Eastman and Peter Laird's original creation.
Where the story will go from there... well, only time will tell. However, it's fair to assume it involves General Krang since the plot allegedly deals with an alien invasion. I know there's still outcry over the leak script, but keep in mind, they've been claiming that's nothing like the final product, the film underwent a rewrite and they changed the title from Ninja Turtles to Teenage Mutant Ninja Turtles. Now, I'm not saying this film will be fantastic or anything, but it looks like concern over the plot can be put at ease for now. Directed by Jonathan Liebesman, Teenage Mutant Ninja Turtles is scheduled to hit theaters June 6, 2014.
*Thanks to lvenger for bringing this to my attention!