Since the cities are black and there is black power, there will likely be no American urban unrest adequate to bring Obama down.
When I look back I see two precedents. Julius Caesar and Caligula (Gaius Julius Caesar Augustus Germanicus).
Julius Caesar was done in by his friends in the Senate. He went beyond what they would tolerate.
Caligula was done in by his Praetorian guard. He made them sick and ashamed of Rome.
Both were inside jobs by those close to the Emperor. Barack Obama knows or has been told of these events. He never strays on any but carefully checked ground. He never dares to be in a crowd. Moochelle aka the Wookie might be afraid to fly with him.
Ping
Yes, and both came from within the established regime. One political, one military. In neither case, was it necessary for the citizens to revolt to oust the dictator.
With the threat Obama's become to his party, I can see the possibility of a cabal forming within the Democrat establishment to destroy him politically, in a bid keep him from doing further damage to the rest of their party. That could (but probably wouldn't) include impeachment.
The scenario of him being ousted by the military is, in my opinion, less likely, but still possible. It all depends upon how far he over-reaches in his quest for complete power in the next three years. If he tries to invoke martial law for any reason, that would be the likeliest trigger.