I agree with your last bit POPS. The Common Market was an early stepping stone towards the design of the technocratic superstate which the current EU is heading towards. None of this is by accident, and the project will continue. In 2015 Junker said “There can be no democratic choice against the European treaties” and he meant it.
If any geographic group of people in the future decide by democratic means that they want to rejoin this superstate I’m sure the opportunity will be created because the UK is a democracy.