the backstop is also the only guarantee the the Irish border stays open
It isn't, and that's just as well because the backstop is very unlikely to ever become law - as such, it is not a guarantee of anything, because legally it doesn't exist.
The Good Friday Agreement is important because it shows intent, but intent is no guarantee for a solution.
The Good Friday Agreement is far more than a mere signal of 'intent' - it is an international treaty that compels the UK and Ireland to retaining peaceful relations. I'm going to keep saying this - neither Ireland or the UK will erect a hard border in Ireland... so who will?
We'll lose access to the single market because we wouldn't ensure its integrity, and set ourselves back 70 years.
Unfortunately this is exactly right. The only thing the EU can do to protect the Single Market if Ireland choose not to do what is asked of them is to suspend Ireland. That would be catastrophic for Ireland, and terribly unfair - but unfortunately it is one of the only things that the EU can actually do about the border issue.
Of course, the EU cannot expel or even suspend Ireland from the Single Market - politically it would be suicide for the EU to punish a compliant member state for something it cannot do anything about. It is, therefore, extremely likely that an alternative solution will be found, as if by magic, that avoids this catastrophic outcome for the EU and Ireland. The form that will take will likely be that the EU agrees to maintain the current trading arrangements with the UK (under GATT 24), while expedited negotiations can (finally) begin between the EU and the UK on a sensible and mutually beneficial trade deal. The fact that these negotiations have been ruled out until after Brexit is, frankly, absurd... and, when you think about it, is really the root cause of this entire debacle.
The preconditions for any deal are 1) the Irish border stays open (as demanded by the UK), 2) the Irish border stays open (as demanded by Ireland) and 3) the Irish border stays open (as the EU allegedly wish too, since that was the aim of the backstop all along, right?). With those three things in mind, the UK and the EU can proceed to work on a future relationship that satisfies those requirements
first. If that means the UK and the EU must trade with no tariffs and with a common rule book on standards, so be it... isn't that what the UK has asked for since day one?
-
Meanwhile, there are reports that the EU are about to offer the UK a further extension to Article 50...