The guys over at Latino Review (via /Film) got their hand on it, and while they didn't post about it, writer El Mayimbe did hit Twitter to reveal a few elements, including that Krang, Bebop and Rocksteady do pop up in the script. The inclusion of Krang seems to suggest the alien elements are still very much in play at this point. The site notes that the Technodrome -- the massive mobile battleship station he built on Dimension X (mentioned by name) to help destroy Earth -- also makes an appearance, and we presume this also points to classic villain Shredder, who assists the body-less Krang in getting a body, will make an appearance too. That posit is bolstered by the fact that Bebop and Rocksteady -- two gangmembers turned mutant by Shredder to help defeat the Turtles -- are also tossed around as well.
That said, it's unclear how substantial the apperances are, but considering these are all the classic characters, it looks like the reboot won't be straying too far from what people know. But with the movie already facing script issues and being pushed back to a May 16, 2014 release date, who knows which of these elements may change as development continues. All we want to know is if April O'Neil is going to be in this or not.