You went from dealing with being banned by google to the general case of an e-mail provider disappearing. This is different. In one case you have control ( choosing not to deal with google because of their arbitrary judgments when it comes to account termination ) in the other, you really don't. ( Random calamity that befalls your email provider ).

If your email provider goes away, you're screwed. Nobody accounts for this situation. Doubly so when you used an identity provider that has gone bust. The question is, how do YOU imagine imposing regulations on mail providers will change anything in a case like this?

Store your credentials, make backups of your emails, don't use identity systems. If things really do go bust, you'll retain access until you can get manual changes made to your accounts.

The other obvious solution is to have identity/e-mail built-in as part of citizenship and be gauranteed by your government.

Register your own domain and point it at your preferred service, if you lose access to that service you still retain the domain and you still have your email address.

If you want to solve this problem you have to spend some money somewhere otherwise you are simply demanding providers give you services, for free, forever, not something that seems realistic?

But can't the same problem happen if you, somehow, lose the ownership of your domain? I mean, I don't know what the actual assurances are, but if there is any chance that you may lose access to your domain (for causes other than forgetting to pay to renew, ofc), even temporarily, that would be the same as being banned from Google. Or even worse, because having your Google account locked means you can't use it but noone can use it either; however, if somebody now has your domain, they could be able to impersonate you.

I think that is very very uncommon and when it does happen there's usually some kind of legal process involved. In other words I don't think you're going to have your domain yanked away without some reasonable amount of warning and ability to dispute.

In the worst case scenario you'd have time to setup a new domain and move everything over. Annoying yes, but again extraordinarily rare.