That is the weakest point. there would need to be an event that proves to the Irish that the English are a double-edged sword- getting their support would only ensure they'd annex you later on. The expansion of England would have to be a little nastier, enough to prove the English only view Ireland as a land that will serve and be oppressed by them for their own uses. The destruction caused by their final campaign would be the straw that breaks the camel's back.
But I think that it will be hard to present that as something threatening to all Irishmen equally as opposed to something seen as the price for those who pick a fight with England.
After all, most of the misery is going to fall on the common Irishman and woman, and few lords are going to stick out their own necks for harm done to someone else's subjects - which is kinda what this amounts to.