This is a game changer. It works really, really well - better than I ever expected to see internet on a plane work. The price tag seems ridiculous, but will probably make sense for a lot of the operators of the planes on their initial STC.
I think the big customers are militaries of nation states. Satellite communications for military drones is a huge enabling technology.
Surely they'll eventually be competing with Viasat for those juicy contracts with the major airlines as well. I won't be surprised if my Delta in-flight internet service is provided by Starlink in a few years. I suspect it wouldn't make any economic sense to retrofit existing planes, but potentially on their newly built ones!