James Gunn clarifies his crossover remarks from Comingsoon's site.
“All I’ve ever tried to say was the Guardians are an important part of the MCU, and they definitely share an existence with the Avengers and other characters in the MCU. But the week after the movie opened I walked into the Marvel offices, and I sat down with Kevin Feige and some of the other folks at Marvel. We had a long discussion about where the Guardians were headed and what was happening to them. I told them exactly what I wanted to do with the sequel to Guardians, and everyone was on board and excited. And, regarding the bigger picture, we all agreed on one thing, and that was to keep huge chunks of the Guardians separate from the Marvel heroes of earth, because they have a whole galaxy to explore. We wanted to use them as a way to make the MCU bigger, not smaller. We wanted to make sure they have their own mythos, as opposed to only one that is intertwined with the earthbound characters. They ARE connected, of course, but that connection would not be the purpose of their stories and fictional lives.’