I think this whole discussion of customer acquisition and whether/when Apple deserves a cut is fascinating.
Sure it will be interesting to see if Netflix take it all the way or roll it back. It will tell you whether the 15/30% commission is worth it to an already very dominant company like Netflix. My suspicion is that Netflix is important enough to many people that they will go and sign up outside the app. I'm not sure that's true for less successful services though.