User blog comment:Arbington/ME3 Theories/@comment-730941-20100628063721

The interesting thing about ME3's potential squadmates is that it becomes extremely complicated to integrate every single permutation of ME/ME2 outcomes while making sure everyone has a roughly similar gameplay experience. Imagine if Bioware gave a unique mission (or even just conversations or dialogue) to all the returning squadmembers. Hypothetically, some players could have as few as four team members (Liara, Ash/Kaidan and the two necessary ME2 squaddies for Shepard to survive). Others could have as many as 15! This would be a gigantic disparity in terms of content, but it could still happen if they were distributed this way.

I'm inclined to think that most of the ME and ME2 squadmembers will appear as cameos in ME3, and we'll have a new squad with perhaps a few characters that are absolutely certain to have survived (Liara, Ash/Kaidan) and ones we've already met before that are also alive (Aria etc).

I think including all surviving squad members as ME3 squadmates (as opposed to cameos) would be too confusing and complex to pull off properly.