Most Americans have at least one streaming subscription.  About a third have more than one.

But there are more than just a handful of streaming services: between streaming video on demand (SVOD) services like Netflix, ad-supported streaming video on demand (AVOD) services like Sony's Crackle,  live TV streaming services (or "skinny bundles") like Dish's (NASDAQ:DISH) Sling TV, sports-specific options like MLB.TV, and many more, there are dozens of streaming services on the market. How many of these can the market support in the long term?

Only a few major stand-alone subscription services seem likely to survive -- but streaming services don't have to stand alone.

Streaming service survival and the hub model

The classic model for streaming services, pioneered by Netflix, is independent: Netflix streams its own content over its own apps, which it builds for different platforms.

But there are other options. Documentary-focused streaming app CuriosityStream, for instance, supplements its own app offerings with other ways to subscribe. Fans can get CuriosityStream through Amazon's (NASDAQ:AMZN) subscription service, Amazon Channels, as well as through skinny bundle services: both Sling TV and Alphabet's  YouTube TV carry the service.

Niche streaming services may need help finding an audience

Image source: Getty Images.

This model provides hope for more streaming services -- and for more choice for consumers. Big companies rich in streaming architecture and marketing reach stand to profit by acting as brokers and hosts for smaller streaming services, while smaller streaming services can target niche audiences without having to spend big on dedicated platforms and apps.

Two types of companies seem best positioned to act as subscription hubs: other streaming companies (particular large ones, like Amazon) and streaming platform companies.

Amazon and the hub model

The hub model has some inherent advantages for all parties, and it seems likely to be the wave of the future. But it also exists in the present, with Amazon Channels being the clearest example.

Amazon has achieved impressive vertical integration in the streaming space. The company has its own streaming devices and streaming platform (Fire TV), as well as its own SVOD service (Amazon Prime Video). In addition, Amazon has dabbled in live TV and been a pioneer of the streaming hub model. 

Through Amazon Channels, Amazon users can subscribe to streaming services other than Amazon Prime Video, whether they are major services like HBO or niche ones like CuriosityStream. The additional subscriptions give users content that is integrated into Amazon's platforms and apps: content discovery and streaming all happen in the same place, and billing is all done through Amazon.

Amazon isn't the only streaming service with hub potential. As mentioned earlier, Sling TV and other skinny bundles can act as hubs, too. Skinny bundles already deal with different channels in a very literal sense. They have offered HBO and other premium networks for years, and they are starting to work with streaming-native brands, too, as the CuriosityStream skinny bundle deals show.

But Amazon's aforementioned vertical integration gives it the inside track -- especially since streaming platform companies are the other major players to watch in a hub-based future.

The streaming platforms as hubs

Amazon isn't the only company that is offering a vision of streaming's hub-based future. Roku (NASDAQ:ROKU) also offers a hint of what a hub model could look like.

Roku is the company behind the eponymous Roku platform, a streaming and media center platform available on Roku streaming devices and smart TVs. Using Roku Channels ("Channels" is Roku's brand-conscious term for apps), Roku users can load up Netflix or whatever other service they'd like.

That's all typical of any platform, but Roku also allows users to subscribe to some services through Roku, centralizing their subscriptions and billing under their Roku account.

It's not quite as complete a hub model as Amazon's, because the services in question still need their own apps for Roku devices -- apps that are much easier for the Netflixes of the world to build out than they are for the CuriosityStreams. But unifying the billing is a start.

Still, Amazon appears to have the inside track. The nature of the Fire TV platform -- which surfaces content on its home screens in a way that Roku's app-menu home screen does not -- makes it ripe for the hub model. If Amazon keeps adding more subscription options, there will be less and less reason for Fire TV users to open individual apps at all: all of their content will be right there on Fire TV's top-level menus.

The future of hub-based streaming

The future of streaming is still unfolding. The hub model is out there, but so are others. Major League Soccer streaming service MLS Live abandoned its own apps, opting to be absorbed by a single larger service -- Disney's ESPN+ -- rather than cut deals with multiple hosts.

Still, the hub model makes sense for just about every party. Roku and Amazon are among the companies best-positioned to profit from a hub-based streaming future, while Google, too, has the streaming muscle and size to be a factor. Meanwhile, smaller streaming services stand to benefit from a model that allows them to serve their niche audiences without burying themselves in overhead costs. Look for the hub model to emerge over the next few years, and keep an eye on the major players -- especially Amazon.

John Mackey, CEO of Whole Foods Market, an Amazon subsidiary, is a member of The Motley Fool’s board of directors. Suzanne Frey, an executive at Alphabet, is a member of The Motley Fool’s board of directors. Stephen Lovely owns shares of Amazon and Netflix. The Motley Fool owns shares of and recommends Alphabet (A shares), Alphabet (C shares), Amazon, Netflix, and Walt Disney. The Motley Fool has a disclosure policy.