FASA who published the star trek roleplaying game back in the 80s, once said dureing the 90s of their game battletech "it's not the future of now, it's the future of the 80s" What this expression ment was that the "path to the future" was written out from when the storyline was first created, and as such some of the earliest events of the timeline may be "dated" this can apply to star trek as well. really we proably shouldn;t apply our history at all to any event from 1960ish on. after all, by now in star trek we've Kicked Khan off earth
TNG:The High Ground provided an allegory for many of the world's frozen conflicts; but to suggest an offhand comment in a TV show in 1990 directly inspired the 1998 Good Friday Accords... well, it is a bit of a stretch even for the most committed of Trek fans.
Your question also starts from an incorrect understanding of the present situation in Ireland. Though the Belfast Agreement did provide for the Republic to renounce direct claims to Northern Ireland and swear off the use of force to that end, the Irish people retain the right to reunify by mutual democratic consent. Contrast this with the Romulan-Vulcan relationship, which has been antagonistic for millennia, with only a peek of hope at the end of the 24th Century. (TNG:Unification II)
Yes but is that ever going to happen? Protestants are in the majority in Northern Ireland and want to stay with Great Britain. Plus the Catholics torment the Protestants in Republic of Ireland. The Protestants of Northern Ireland are never going to cut a deal with the Catholic majority of Republic of Ireland
The problem had always been the Catholic minority in Northern Ireland....