Space-based ADS-B is now a thing. It is used for coverage of the north Atlantic.
https://www.navcanada.ca/en/air-traffic/space-based-ads-b.as...
https://www.navcanada.ca/en/air-traffic/space-based-ads-b.as...
It's a very exciting technology, sure, but I think it's many years of testing and flawless operation as a secondary data source away from replacing ADS-C on oceanic routes.