What would be the most likely PoD and ATL leading to a Protestant France? Perhaps the creation of "protestant republic" in the south in a post-Saint Barthélemy (1572) reaction? Henri IV deciding not, finally, to abjure Protestantism (1593) and then going on to take Paris all the same (and what's more failing to be assassinated in 1610)? Is there any plausible scenario that might have led to the establishment in part or all of France of an official Protestant or reformed church?