Unionists seem to be hanging on by the tenuous thread of Scotland remaining in the UK. I see no future for their cause if Scotland leaves. Even if they do, London simply doesn't care about them. Priorities are converging and England is in many ways a post-imperially deluded, with a seeming death wish towards it's own civilization.
If the Northern Irish have sense, they will leave behind the narcissism of small differences, not be beholden to British divide and rule, and save themselves from a Britain being destroyed that doesn't care about them.