I mean Netflix could actually sort out the viewing habits and see who gave it a try and then stopped, and who ended up hooked and watched five episodes the same afternoon they watched it for the first time.
That's super powerful in my opinion.
Netflix will indeed have some of the most powerful analytic tools available to apply to their programming, but we have no way of independent verification. Well, I suppose they may break it down in a quarterly report, but they may not have any reason to.
I think lots of people are interested in the viability of this model. Television format entertainment hasn't been significantly "disrupted" by the internet yet and this could be a step in a new direction, but it'll be hard to tell without Netflix releasing their numbers.