I've not seen anyone advocating the second option, I merely presented it, given that a customs union or reversal of Brexit are not even remote options currently. This then brings things around to a United Ireland, as the only player in town to avoid a hard border. Maybe the UK will ride in late on and surprise us all, or maybe unicorns will fly, one never knows.Stop being silly, Ted. The idea that anyone who matters would like Ireland to rejoin the UK is for the birds (I'm probably putting it more politely than the idea deserves).
There are three choices: a reversal of Brexit (or Britain at least remaining in the Customs Union), a customs border on the Irish Sea or a hard border.
Of the three, a customs border on the Irish Sea seems to me the least likely.
One wonders, though, what'll happen after the next election in Britain.