If Obama were to become President, it seems very well possible that when he is made fun of, vanity would be the recurring theme.
MadTV used a different theme-- that he is like a Jack Bauer/Chuck Norris joke kind of persona who can do everything and is perfect in every way. It's similar to
Barack Obama Is Your New Bicycle. I think the way to mock Obama on TV shows is to use the celestial choir approach, but to do it better, like a televangelist turning his rallies into church meetings with an organist. It's very hard to really nail down. The comedy in the MadTV skit and in others I've seen have been about laughing at the people interacting with Obama, not Obama himself.