These additions would enrich an overflowing treasury at Disney, whose assets includes Star Wars, Marvel, Pixar, ABC, ESPN, the world’s most popular amusement parks, and, of course, its classic animated-film division. When Mufasa tells Simba in The Lion King that “everything the light touches is our kingdom,” it isn’t just memorable screenwriting. It is corporate guidance.

The deal allows Rupert Murdoch, the billionaire patriarch behind 21st Century Fox, to consolidate his own kingdom—and his legacy—around the very place where he got his start: news. Murdoch, who built his $100 billion business starting with a single newspaper in Australia, would retain ownership of the Fox broadcast network, the Fox News Channel, and several national sports networks. Like an aging King Lear dividing the spoils in his twilight years, one of the world’s most famous media moguls is selling off his accumulated fortunes.

At the deepest level, this corporate marriage isn’t about Mickey versus Murdoch, or Avengers versus X-Men. It’s all about Netflix—and, to a subtler extent, Google and Facebook, whose dark shadows extend over the entire media landscape.

Streaming video has conquered pay TV and created a generation of cord-cutters; the youngest Millennials (those in their late teens and early 20s) watch 50 percent less traditional television (“cable TV,” as it’s commonly called) than people that age did in 2010. That means every content company now has to be a streaming technology company. As eyeballs shift away from the cable bundle, advertising is following them to mobile devices, where Google and Facebook have built an impregnable duopoly. That means every ad-supported television business has to become a direct-to-consumer business.

For media and entertainment companies, there is one big existential question: Get big and stream, or give up and sell? That is a choice that motivates both this deal and AT&T’s troubled bid for Time Warner. By making huge acquisition offers, AT&T and Disney have chosen Door No. 1. Disney’s future hinges on whether it can build a streaming powerhouse, or “Disneyflix”—a direct-to-consumer television product that, like Netflix, distributes a library of video over the internet to phones, tablets, and TVs. The company plans to launch an internet sports product in 2018 and—most importantly—a filmed entertainment product in 2019. To truly compete with Netflix, Disney’s 2019 service will need both a deep library for viewers ages 1 and higher (some viewers just want old shows and movies) and an excellent television production company (some viewers prefer new stuff). With this deal, it would have arguably the world’s best in both categories.

By agreeing to acquisition offers, Time Warner and 21st Century Fox have chosen Door No. 2. The latter group has seen a vision of their future—permanently falling live-TV ratings, more cinematic flops, quarterly job-cut announcements—and rather than wake up every morning in a hot sweat for the next 10 years, they’d prefer to sell high as fast as possible. Time Warner wants out of the movie business. 21st Century Fox wants out of the regional-sports-network business. It makes sense to sell to skittish behemoths that are both desperate and flush.