It is inevitable that NI will join the Irish Republic in some manner as a special devolved state, but it will happen naturally as the demographics shift from the Unionist to the Republican side as per voting and the younger generations identifying as unionist will care less about the parades and bonfires and far more pressing things like economy and opportunities in Ireland and EU.

Nobody wants to go back to the "troubles" except for the hardcore old timers who are slowly dying out on both sides.