User blog comment:Arbington/ME3 Theories/@comment-1679409-20100702231529

I think Liara will be the only returning squadmate. Every other squadmate has a possibility that the'll die. The work needed to work squadmates into the game that may not be available because they died in a playthrough would be massive. Notice that the decisions you made in ME1 only play a small role in the gameplay experience for ME2, a few cutscenes, some dialogue differences, etc.

Plus, Bioware likes to have mostly new squadmates in their games. ME2 only brought back Tali and Garrus as squadmates. Dragon Age: Awakening only brought back Oghren I think.