Personally, I say it will never happen, as the impeachment process itself would probably take far longer than the time remaining in the Kenyan statist's first (and hopefully only) term.
Another reason is that the repubs simply don't have the balls, and are unlikely to grow any anytime soon, even if they were to put enough fannies in congress this November to actually be able to do it.
I can think of a whole host of reasons why Barack Hussein Obama should be driven from power, as he has been steadily defecating on our nation's founding document since 12:01 pm, January 20, 2009.
Whether he one day winds up back in Chicago stapling 8.5 x 11 sheets of paper to utility poles (perhaps the only thing he is any good at), or gets whisked off to some private island somewhere to spend the balance of his remaining days picking the lint out of George Soros' belly button, that day will be a good day for America - however much is left of it.
That day cannot come soon enough for me.