If the UK does that, the EU must and will implement a hard border between the IR and NI to prevent the UK using a hidden backdoor into the EU common market. Its not relevant whether I like that or not - that is what from a purely functional point of view the EU must do to prevent that, its the only way. Thats is the termination of any trade deal between the EU and the UK.
Think I stockpile another year's reserve in Q10 then.
The Irish issue was the big trip wire in all the Brexit agreements and negotiations from all beginning on. They ignored it and hoped the fairy queen would solve it magically for them. Did nobody ever tell them that fairies do not exist?
This was to be expected.