Urmstongran, if Johnson has accepted that there cannot be a border in Ireland, then he must have also have accepted that there has to be a Customs union on the island.
That Customs Union if not incorporating the whole of Britain then in some way it has to be worked out how could be made to apply to just Ireland, and in that still protect the integrity of the EU free trade area.
Whatever the outcome of the above negotiations (if the reports of Johnson climb down are true) then the ERG group, DUP and the Brexit Party will never accept such an outcome.
It will be chaos in the House of Commons once more, and the Brexit Party will be fighting every constituency in the forthcoming General Election and all will have a view to overturning the agreement.
As stated, if the reports are true, the crisis could be a long way from over. However, for me, Britain remaining in the Customs Union would be the best way for Britain to actually leave with the least possible pain.