Well said, mate. Even though I think partition in 1921 was unfortunate, a united Ireland from anytime after the troubles began would have ended in an unimaginable bloodbath. The levels of doublethink that went on in Republican circles in that regard were truly astonishing. They knew the belligerence and intolerance of much of the Unionist population, that was much of the reason for the IRA's reemergence ffs, and yet they collectively seemed to imagine some sort of peaceable nirvana going forward, once the six counties were subsumed into the Republic. That Unionists would accept the change with a mere whimper. It's a way of thinking that borders on the insane and shows how the romantic notion of a united Ireland seemed to cloud all logic in many Republican supporters.
As you say, it would have resembled the Balkans which the Irish state did not have the resources or infrastructure to begin to cope with. I suspect the Yanks would have had to intervene militarily.