The idea has taken root that the President is held captive by the need for 60 votes in the Senate, but his executive powers extend far beyond that. He can issue executive orders, rules and regulations, he has the power of appointment, and he can negotiate executive agreements with foreign countries.
Of course, a large part of the population is already alarmed by Obama's demonstrated creativity at finding ways of getting what he wants, whether or not it is legal or constitutional; for example, the Gulf oil drilling embargo, in defiance of a court order against it, and his many appointments of White House "Czars" as a way to avoid Congressional oversight. If Obama, after losing the Congress, goes down the road of ruling by decree rather than consent, I think he's going to find himself facing an even larger and angrier opposition than he has now. This would be a situation that I think he would have little ability to control.