I don't think the anti-gun forces have the votes to get anything through Congress. If anything gets done, I think it will be through Executive Order. I did a little research on Executive Orders, and it seems that a precedent was set in 1952 when the Supreme Court overruled one of Harry Truman's orders. The court said the Executive Order was invalid because it attempted to make law, rather than clarify or act to further a law put forth by Congress or the Constitution.
Since then, Presidents have been careful to cite which specific laws they are acting under when issuing new executive orders. I'm no legal scholar, but I think Obama would be on thin ice legally if he goes the Executive Order route. Of course, that might not stop him from trying. I suppose it could take years before the issue was decided in the courts. Meanwhile, we'd be *****ed.
Anyway, there's an article about Executive Orders at Wikipedia: