So Bioware is giving us a "modified" ending to Mass Effect 3. While details are scant, the safe money is on not a changed ending, but an epilogue of sorts. Something more.
If you were hoping that would mean something more from a certain Commander Shepard, well, it doesn't sound like it will. Speaking with Edge, Jennifer Hale, the voice of Shepard, said that she hasn't recorded anything. She hasn't even been contacted by BioWare or told she'll be needed for whatever new content we end up with.
Not that she won't ever be contacted in the future, but given the timeframes needed to put DLC together, it doesn't seem likely Commander Shepard will have much of a role to play in whatever new content is added to the game's "ending".
Jennifer Hale on Mass Effect 3's ending [Edge]