I can't imagine the world where Netflix, Amazon, Disney, and HBO all coexist.
If you take Disney (less ESPN) and HBO specifically, they're pretty much diametrically different brands so it's pretty easy to see them coexisting.
Some of the most ambitious players right now may have to scale back, and the "deliver it all to the same place" problem that's been present ever since cable-alternatives started popping up is mostly unsolved (though some of them are starting to tackle this, as are companies like Apple and Roku) but the number of channels is hardly new.
Amazon and Netflix are the wildcards given their smaller original content.