While Mass Effect 3 generated its fair share of controversy, I would honestly be fairly surprised if there was no interest in new DLC, and I suspect fans will be pleased by knowing that BioWare teased another one at this year's Comic-Con with a single image.
Aside from reporting the news, Joystiq also had the chance to chat with producer Mike Gamble, which seems to hint it will be a single-player affair:
So, what's next for Mass Effect? Producer Mike Gamble showed off one picture of future Mass Effect 3 content in his panel at Comic-Con, and from what he told Joystiq it seems to point to more single-player DLC. "We want to do single-player DLC," he said. "We want to do single-player, maybe more multiplayer if people still play it."
That single-player DLC, whatever it is, will still be about Shepard, not someone else in the universe. "Mass Effect 3 is Shepard's story," said Gamble, "so the single-player DLC for Mass Effect 3 will probably focus around Shepard."