Now that I've had had some time to think about it. I wonder if there's not a possible french dissolution PoD in the albigionese crusade.
When the crusade turns against the count of Toulouse, what if the french king, instead of siding with the crusade, steps in to protect his vassal, as was his feudal duty?
At that point, the crusade had an important army, which can oppose the royal troops. Then, if the papacy, warned by previous conflicts with french kings ( when Phillip II was excommunicated and had his kingdom placed under interdict, he just sent his soldiers to open the churches again ), uses the ultimate weapon at it's disposal : it absolves every french lord from his oath to the french king and declares excommunicated every man obeying the french king.
That could lead to a nasty civil war, which, if the King loses it, has the possibility to lead to the kingdom being fractured in several mid-size components ( or, of course, it could just lead to a change of dynasty ), if the crusaders prevail. Of course, if the king prevails, then the authority of Rome is set to naught and you can expect a lot of national churches to form.
Of course, these high stakes are a reason neither king nor pope wanted to go there OTL, so it's difficult to make this pass, but maybe not impossible.