What does the Netflix streaming service have? A brand name and some servers. That's it.
Technically, since they use Amazon for servers, all they really have is a brand, but that's a bit beside the point.
I like to think of Netflix as the HBO of streaming. They simply provide a single interface to get access to a mix of old and new content of varying quality. They will have competitors (maybe Amazon will become the Showtime of streaming), and there's nothing keeping the studios from going direct to the viewers (FX, or DisneyChannel).
But the studios still need Netflix for revenue the same way Disney still sells movies to Stars even though they could easily put them on the Disney Channel. Some people will only pay for one or two subscription sources, and if Netflix is still on the top of everyone's list, then the studios will continue to license them movies.