The UK is not member of the EEA solely because of its EU membership. The UK is an individual signatory to the Agreement.

In your last paragraph you appear to imply that the other members of the Agreement can expel the UK from the EEA. No such provision exists in the Agreement. There is however a procedure to temporarily suspend a member (Article 102) in case it fails to implement the required legislation. As long as the UK complies with its obligations it can not be suspended this way. I expect the ultimate decision on EEA membership to come up to the European Court.

I follow the British media at some distance, but close enough to understand that membership of the EEA remains an hot topic. The Government itself has vented the desire for a "transition period" during which it would remain in the EEA.

You might find me At The Edge Of Time.