In otl many things went wrong for crusaders but wi Louis slays Baibars on the battlefield. What are the ramifications of no baibars. Plus how much land can crusaders capture
The crusader states in Holy Land would have lasted much longer.
The big question is was there someone who could defeat the Mongols in the area to replace Baibars. If so then if they were Muslim I guess they replace him in history (expansion of Mamluk empire etc.)
More interesting would be if the person was Christian. Having defeated the Mongols he would be in great demand in Europe. If it was a member of one of the Knighly Orders then it would have changed their histories hugely.