And it's not like my news app can't make 50 http requests to do good-enough aggregation itself, for free.

Well, radio stations don't earn a lot either, but still have to pay licence fees for the music they play. Perhaps some sort of flat fee paid based on some statistics how much content has been shared from which source would make sense. It will not be a huge money, but it's still better than no money at all. Aggregators/ search engines need the content produced at the volume, otherwise they'll be out of business too at some point, so it can be mutually benefitial.