I mean, it would be somewhat in character for the UK to attempt to achieve that unilaterally and with no consultation, but I think that to try and just 'give it back' as a solution to Brexit is, while no doubt well intentioned, still representing a bit of a colonial point of view.
"It is the firm will of the Irish Nation, in harmony and friendship, to unite all the people who share the territory of the island of Ireland, in all the diversity of their identities and traditions, recognising that a united Ireland shall be brought about only by peaceful means with the consent of a majority of the people, democratically expressed, in both jurisdictions in the island."
Expect a vote for a general election tomorrow.
If they can't get a super-majority, I think they might be stuck with waiting until term, absurd and broken though that is.
The Lib Dems weren't thinking at all when they pushed for fixed terms.