Also Disney is currently in a strong position for this right now. They released ~10 movies in 2016 and had the 4 highest grossing films of 2016. This, of course, assumes that Marvel and Lucasfilm properties are put on the Disney streaming service (I would expect that Touchstone label will not be included in this, as it's always been distinctly branded).
Either way, $10 per month is a bit steep up until the point that they stop selling discs; right now it's not much more than $10 per month to buy every single new release on bluray, and it's less than $10 per month to buy them on dvd, if you shop around.
The thing that scares me is that this puts them in a position where they could stop selling media altogether, and it's no longer possible to pay a flat fee to watch a movie any time you want. At that point the only competition with the streaming service would be piracy.