Because the situation in Ireland is just the same as it was in the 1920s.

Too much autonomy and the Internationale ideal becomes all the harder to move toward. It's already hard enough having a Europe with a trojan horse of English manufacture working hard against; regionalizing further complicates things (and bear in mind that autonomists do not tend to be Internationalists or Europeans, in fact, quite the contrary...)

All this being said, I recommend this diary on the basis of a pretty cool-looking map and all those cool looking flags (though you could write a diary on the historicical bona fides of regionalism by researching some of them. I think the Breton flag, for instance, is of quite recent vintage, probably spurred by the relatively recent drive to make French not only lingua franca in that part of France, but also totally supplant the Patois).

Fai de bèn a Bertrand, te lou rendra en cagant

More likely than your scenario of Northern Irish protestants being hunted away is an independent Protestant Northern Ireland of reduced territory.

_{*Lunatic*, n.
One whose delusions are out of fashion.}