Originally Posted by cherokeesam
The only characters officially listed for GOTG so far are Star-Lord, Drax, Gamora, Rocket, and Groot. When pressed about Warlock/Magus (as well as other Guardians) on several occasions, Feige and others have demurred.
In other words: if Warlock wasn't officially listed as part of the cast in the first place, then believing Marvel/Gunn will change their minds about it later is just wish magic.
It's quite possible he can be a supporting/advising role ala Nick Fury. He's just not on the combat team. He typically had the role in the comics: Infinity Gauntlet in particular.