I had thought about something similar, only with publishable subscriuptions so N people could share the same clipboard. Only I wanted the opposite: It would be ephemeral, only as long as you subscribed to the ‘feed’ would you see what was there, there would be no history, and pragmatically, no long term retention in the cloud…mostly as a cost savings measure.

I got so far as thinking you’d have two guids: One to subscribe to, and the other to revoke the feed.

It never got past the thought stage…and I made a logo and registered a URL that I’ve since let expire as the coding took longer than my attention span.