Saddam blowing up Baghdad is not going to cause this fantastic uprising of Jihad.
What about the Fatwa's issued by Iraqi's AGAINST Saddam, a SECULAR leader? I would think the words of the most repsected religious leaders in Iraq will carry some weight in the arab world, even Osama himself says he wouldn't be to displeased to see Saddam go. You act as if the whole middle east is rising to help him, you speak of "reinforcements" ( i think they blew up that BUS too), those are small bands of people ALREADY that committed, Saddam calling for Jihad is not going to get any reaction from anyone who wasn't ready to do such an act anyway.
The Arab world will blame Saddam more so than anyone if your scenario plays out, you forget he is not a religous man himself, and his regime has oppressed, tortured, and killed more muslims than any western nation.
What happens when the rest of the Arab world sees how happy the Iraqi people are that we are there? What happens when they see how our efforts so quickly produced a viable, prosperous country in which all muslims led a good life?