I'm not sure anyone wants to ignore the impeachment provisions that are part of the Constitution. I think it could be argued that they are not relevant because they apply to the President (among others) and Obama cannot be the President because he is not eligible to be President. I also think that if there were talk of impeachment, whether relevant or not, you'd wake up one morning to find Obama back in Kenya for good. Even Nixon wasn't impeached.
ML/NJ
Not a lot of conservative legal scholars embracing that interpretation of the constitution...(outside of a few freeper birther legalists)...but have fun stormin' the castle!