User blog comment:FridgeRaider88/Mass Effect 3 Squad Speculation (spoilers)/@comment-730941-20100904064038

Not to interrupt everyone's interesting discussion, but...

All of the ME2, and some of the ME squadmates could be potentially dead. Bioware would not write and record a game's worth of dialogue for 15 characters that may or may not even be alive in most/some/everyone's imported games. It's foolish to assume that most players kept all squadmates alive, and would import that save if they did - a certain percentage of players are going to have thousands of combinations of characters, from as few as two ME2 survivors to 12.

With this in mind, I'm thinking new characters with the ME/ME2 squadmembers making cameo appearances. Anything else would be ridiculously difficult and futile for Bioware to pursue.