Please correct me if I’m wrong, but didn’t the IRA get one thing it wanted when the British removed the troops stationed there?
Getting British troops out of Northern Ireland was something really obvious and highly symbolic. But the IRA long ago threw its fate in with left-wing radical groups and became atheist-Marxist radicals, and have more in common with many of the ME terror groups.
...and Europe, for all if its flaws, also gave the IRA much of what it wanted, including open borders and a much reduced emphasis on Westminster.
It is true that there is not just a single currency on the island, but that is not the fault of the UK. Ireland is on the Euro and NI on the pound. There is not a single, sovereign government over the entire island, but nor is NI just simply dominated by Westminster. As everything shifts to Brussels, seems that the Republicans get some of what they wanted, and lose some of what they wanted but in a way which makes those goals simply gone forever.
Either way, Europe (among other factors) has taken the air out of the Republican balloon for good.