User blog comment:Arbington/ME3 Theories/@comment-1221773-20100717025517

Another tangent: how likely is it that all 15 potential squadmates from the first two games will return as squadmates in ME3? I think what'll happen is there will be some behind-the-scenes calculations (or even a manual selection scene) upon file import which predetermines which squadmates will return and which will only make cameos; that way, every playthrough you do might involve a different combination of squadmates.

In my opinion, we just have too many squadmates as is for BioWare to use them all at once. We also have to consider new squaddies that may be introduced.