....Legally speaking things then revert to the status quo including the UK's opt-outs...
You are missing that the EU in on a road of constant evolution of its constitution, rules and goals, moving towards “ever greater union”, i.e. federalism.
The calls for reform are heavily weighted towards the federalist aims and the big players in the game are almost all of that persuasion.
As David Campbell’s “concessions (remember them) were never ratified and are now effectively defunct, the UK is not immune from future reforms or decisions that go against it own national interests.
It’s arguable that it would not have been immune in the long run, regardless.
For example, there are moves to include non-eurozone members in being equally liable (with the euro-zone members) for bailing out the euro, because the debt burden is so high.
Qualified majority voting comes in soon and removes invidual members veto in almost all matters, other than defence and foreign policy.
The intention is that those two areas will lose veto rights in due course as the EU defence force and its associated ministry are established, which will lead to removal of defence provision and policy from the remit of individual states.
Also, there is an ambition for the union to establish its own central foreign policy regime, superceding that of the individual member states.
These changes are not simple enhanced cooperation between member states, but transfer of total authority to the EU institutions.
There’s a whole lot of reading on policy to ultimately transfer “competencies “ from individual member states to central control .
This is not fantasy or science fiction.
At the moment there is slow progress on such matters, but it’s coming in due course unless something interrupts and changes the fundamental ambitions of federalism.
