It is known that Charles Stuart, in 1750, realising the impossibility of regaining his crown as a Roman Catholic, received Anglican communion while travelling incognito in London. However, the planned French invasion of Britain to restore him during the Seven Year's War failed to materialise as a result of French naval defeats.
So if the Young Pretender had come to the same conclusion before the rising, would it have had any effect on the final outcome? Who might have supported him who did not IOTL? Who, whose support he did have IOTL might have opposed him? Would it have ended French support which was key to the near success he had IOTL?