I never bought into the theory that the Guardians would be in A2. Seems like it's official that they won't be. Here's Whedon talking about it:
"We’re following Guardians at Shepperton [Studios, with Avengers 2] but we won’t be swapping cast members. Every movie is its own thing and has to be. Unless I take a lot of peyote and write a very different draft… and I’m not ruling that out."