There is a huge flaw in your theory. It is the flaw that is also why Biden has not already, and will not be replaced. Your theory requires the recognition by Obama, that Biden has screwed up, probably in an illegal manner. That would obviously mean that Biden was a poor choice in the first place. Obama cannot admit that he made a mistake, (other than admitting not being able to make us unenlightened minions understand his complete excellentness) therefore he cannot possibly use your scenario as a credible ruse. It would require him to do something that is truly impossible for a narcissist of his level.