The EU will reject any suggestion that doesn't involve keeping Britain in the Customs Union: their attitude may begin to change only when they realize that it jeopardizes the €40 billion bribe from the UK that they're relying on receiving.
In the end a fudge compromise will probably be reached that involves recognizing that because the UK and EU have more-or-less identical standards there is no need for a hard border and the authorities will just have to turn a blind eye to any Irish cross-border smuggling - as they already do.
In the end a fudge compromise will probably be reached that involves recognizing that because the UK and EU have more-or-less identical standards there is no need for a hard border and the authorities will just have to turn a blind eye to any Irish cross-border smuggling - as they already do.