This is going to play out in a very strange way. If the UK is being constrained by the agreement here to accept EU law, they may be able to twist an FTA deal out of the wording without the four pillars being imposed, as it will be seen as a necessity being imposed by the EU via Ireland.
I.e., the EU can't demand the UK both maintain harmonization in Ireland and deny them the market access which that harmonization requires after leaving.
(not saying this will happen, but it seems like an obvious negotiation strategy from the British side).
This is going to play out in a very strange way. If the UK is being constrained by the agreement here to accept EU law, they may be able to twist an FTA deal out of the wording without the four pillars being imposed, as it will be seen as a necessity being imposed by the EU via Ireland.
I.e., the EU can't demand the UK both maintain harmonization in Ireland and deny them the market access which that harmonization requires after leaving.
(not saying this will happen, but it seems like an obvious negotiation strategy from the British side).