There is no way the SCOTUS can "dethrone" remove, or cause to be removed, the POTUS.
They can rule on the Writ of Quo Warranto, on appeal from either side. But no matter what their finding, only Congress can remove a sitting President, by Impeachment in the House, and Conviction in the Senate.
Many thanks! I hope this spring you get eat your share of fiddle heads...delicious.
Anyways, the best way to trip up 0bama is for one or more State Attorneys General to demand proof of eligibility in 2012. If you want to run for President in our state you must prove eligibility
But they could rule that he is not, and never was eligible, and thus was never POTUS.
Only the President, Vice President and all civil Officers of the United States may be impeached. If he's not President, he can't be impeached. Besides which, is being ineligible Treason, Bribery, another high Crimes or Misdemeanors.
I'm being a little flippant, but it is uncharted territory. The founders neglegeted to say how someone who slips by, but is discovered to have been ineligible, is removed.