There aren't many English in Ireland so if they left it wouldn't make a blind bit of difference.
Anyway, the troubles ended on 9/11. The IRA knew they couldn't kill toddlers in Shopping Malls and still expect American sympathy.
Northern Ireland is part of the UK until the people of Northern Ireland decide otherwise. That is accepted by the Republic of Ireland, Britain, the DUP, UUP, SDLP and Sinn Fein.
We will just see how long that lasts. My bet is not long.
And don't imply that the IRA are more guilty than Ian Paisley and his Orange scum. They are not.