People who produced content were at the mercy of distributors because they held the keys to people accessing their content. What changed things was when people started realizing the power of the Internet. First it was how News was delivered(hence why Newspapers have been dying in droves) and now its changing the TV landscape. When companies like Netflix broke into the scene and started making their own content while utilizing the Internet to give their users access through their smart TV or PC, it basically circumvented the traditional TV Media relationship and that is why Netflix is considered to be a powerhouse now.
What is happening is that companies with the means to do so(first CBS and now Disney(who owns ABC and other content providers such as Marvel studios)) are following Netflix's path by offering their own "service". In other words, the people who created the content are now getting into the business of distributing it themselves and in the manner that Netflix started. The people who have to adapt are distributors like Cable Companies who have to face increasing numbers of people cutting the TV/Cable cord in favor of Internet streaming. Fortunately for some Cable providers, they also do Internet but it means less revenue for them in the long run(thereby forever changing the balance of power in Media). The real question is whether Internet companies have the right to change how quickly data is transmitted depending on what site or service you're trying to access(aka Net Neutrality issue). If Disney buys out an Internet company or two, then they'll control not only the content but the means at which to distribute it(and perhaps restrict their competitors, which again brings up the whole Net Neutrality crap).
Also with them now hosting a service with their content, we shall see what effect that has on Netflix, Hulu and even Youtube where content is posted online for people to watch.