Actually one of the reasons that the crusaders were able to take palæstina, was that the muslims had alot of internal stride, so if as we assume that saladin would not be able to hold his position after mecca had been sacked, I belive that all those who whom earlier on had power(Al-Adil), or wanted power(saladin's sons) would split the country in many camps, and if the Crusaders after this played their card right, as the first crusaders did, they could have kept the states for quit a while.