In spite of the GOP being a horrible party (only looking good in comparison to the more horrible Democrats), I hope Obama isn’t shown the door until after the GOP has control of Congress.
Why? After Nixon resigned, in August of '74, the Democrats won big time in the November elections, leaving Gerald Ford with an even more Democrat Congress. Then in '76, we got James Earl "Mr. Peanut" Carter, for President.
Thus the fallout from The One becoming "former", would reach both the '10 and '12 elections, and would increase the chances of a Republican takeover of Congress. Increase them a lot.
It would also mean that Biden, or whoever became President, would be "credited" with a full term, under the XXIInd amendment. Not it would be at all likely that the person would be elected in their own right in 2012. However he would present a very weak opponent for the 2012 race, just as Gerald Ford was in '76.
The only advantage to "the end" being after January of '11, when the new Congress was seated, would be that the new Congress, rather than the old one, would provide the confirmation of the selected VP replacement required by Amendment XXV.