Actually Netflix and Kindle were doing just fine before they came out with iOS apps. As was Sirius, Skype, and many other providers with subscription-based services that can be accessed on multiple platforms.
iOS is not the main focus of many of these services, being able to use them on your phone/tablet is just icing on the cake. All Apple is doing is hurting customers.
Actually, Sirius was not (and isn't - as is evidenced by their stock) doing fine. No one actually knows how Kindle is really doing because Amazon doesn't break down sales. But you can bet that iOS readers are a major portion of its ebook customer base. Netflix, too, got a big boost from iOS streaming.
The fact that these things CAN be accessed on multiple platforms doesn't mean people ARE doing so.