Bay promised that the sequel will feature a lot more actual Transformers, but he certainly isn’t dialing back much on the human components. The Hollywood Reporter has confirmed that a bunch of the original Transformers cast has signed on to return for the sequel. Megan Fox, Josh Duhamel, Tyrese Gibson and John Turturro will reprise their roles in Michael Bay’s Transformers 2.
I think it has always been assumed that Fox would return as Sam’s girlfriend (or possibly ex-girlfriend). I’m also not surprised that Duhamel and Gibson are being brought back as the human faces of the military, especially since they have tactical experience battling the big robots (or at least that’s what I hope the storyline military’s explanation is, because if Duhamel and Gibson’s characters just happen to be in the right place at the right time, that would be really sloppy screenwriting). I am somewhat shocked that Turturro is being brought as his s7 role seemed to polarize audiences. Some people loved him, some thought he was annoying and took away from the film.