Even if most of the people were willing to give up the NHS
I'm not Irish at all, and it wouldn't be any of my business if NI did want to leave the UK (regardless of whether to join with RoI or to go it alone) - but as somebody who has never not lived being covered by the NHS (and maybe my opinions are coloured by being a heavy user of it by necessity), I think it would be a huge wrench for somebody to have had that and then willingly give it up.
I presume that, if/when Scotland goes it alone, they would/will have their own NHS run on broadly the same principles of the current UK-wide one, but if Ireland re-united again as one country, it would surely be NI falling in and harmonising under Dublin's existing system of governing principles rule rather than the other way around?
Just out of interest, is there any groundswell opinion or desire for Welsh independence?
In theory, I suppose England could decide to leave the UK (not sure what it would achieve, though) - that could be interesting! I wonder how that would pan out having a united tri-nation country of Scotland, Wales and NI without one massively dominant nation. Could be a massive success or a huge failure, who knows? Not that it would ever happen!
The Queen is 94, and I cannot imagine any U.K. government allowing any possibility for the break-up of the U.K. during her lifetime. For the same reason, I don’t think there will be another Scottish independence referendum in her lifetime.
Without wanting to speak too controversially, the question was about 'by the end of the decade' (yes, I know it technically ends on 31.12.20, but not in common parlance). That's 10 more years and the Queen is, as you say, already 94, so I don't think anybody can necessarily guarantee her seeing 2030....