No, it just matters if countries are willing to implement consequences for non-membership. And that's frankly a pretty trivial thing from a political and techni

No, it just matters if countries are willing to implement consequences for non-membership. And that's frankly a pretty trivial thing from a political and technical perspective, so I'm assuming it'll come. Various countries already have lists, e.g. the EU has lists for 'non-cooperative third-countries', which can be used by member states to add witholding taxes for transactions with these countries in-particular as a preemtive measure to reduce aggressive tax avoidance. Ireland is not joining this agreement for no reason, they're doing it because non-membership will hurt them more in the end.