The only thing stopping the Democrats from impeaching Bush is that Cheney would become President. They're trying to convince the Republicans to oust Cheney for them, and then they will go after Bush. Even if Bush nominates a replacement, the Democrat-controlled Senate could hold up the confirmation long enough to oust Bush and install Nancy Pelosi as President.
How's that for moonbat theorizing?
While your main point is correct, the procedure you mentioned is not, according to the 25th amendment to the Constitution:
Whenever there is a vacancy in the office of the Vice President, the President shall nominate a Vice President who shall take office upon confirmation by a majority vote of both Houses of Congress.