It just seems like the cache hit rates would be dismal if it had to handle so many content providers and such a wide range of content, even if you had some Hollywood-doomed way for e.g. Netflix and Hulu to use the same cached MP4 for titles which they both offer.

I don't see how that could work without some protocol where e.g. Netflix, et al. could preload content in advance and how could that work – voting at the gate, only being able to see the top n most-popular on <service>?

This is actually kinda what united is doing with their in-flight entertainment system. It's a limited selection of movies that you can stream. I am assuming it doesn't need internet to stream them.