You keep using that word, "impossible". I do no think it means what you think it means.

Maybe all these paywalled sites could start a subscription service where you pay one low monthly fee and get access to X sites with it.

Then every publisher that is a member of the subscription service gets an amount of money proportionate to the number of subscribers that read their articles.

Seems so obvious to me but maybe there’s a reason why it wouldn’t (or hasn’t) worked.