Premium cable channel Showtime, which airs intelligence thriller "Homeland," starring Claire Danes, is now available as an add-on subscription to Amazon Prime customers. Showtime/Stephan Rabold

The year is winding down, but the Great Streaming Wars are still ramping up, and Amazon Prime has fired the next shot: You can now get a Showtime or Starz subscription with your free two-day shipping for an extra $8.99 a month (each). The two networks aren’t the only streaming services being offered as add-ons in Amazon’s “Streaming Partners Program,” but they’re certainly the most high-profile ones. Others include the Lifetime Movie Club and British/Australian series repository Acorn TV.

Offering a stand-alone service has become de rigueur for premium cable networks. HBO launched HBO Now in April. Amazon Prime competitor Hulu began offering a Showtime-over-the-Internet subscription for $8.99 a month in June as an add-on for its paying customers; Showtime launched its own stand-alone Internet-based subscription, à la HBO Now, in July for $10.99 a month. And on Monday, at an investor conference in New York, Leslie Moonves, CEO of Showtime parent CBS Corp., praised the unshackling of Showtime from the traditional cable bundle. “[Cable-based] Showtime is only in 24 million homes,” he said. “That’s the future of Showtime: over-the-top.”

Starz had yet to take that big streaming step, though CEO Chris Albrecht had told analysts at the end of October that deals with certain distribution partners were imminent. In the past, episodes of, say, “Outlander” were available to stream only for those who shelled out not jusst for cable, but for Starz as well, which generally costs around $10 a month. Now, for a dollar less, viewers can experience all the Scottish time-traveling shenanigans they want.

Room For More

HBO and CBS (which calls its ad-supported, Internet-only service CBS All Access) had no comment on when -- or if -- they’ll be joining Amazon’s merry band of streaming add-ons. CBS' Moonves has said several times he’s considering an ad-free version of All Access for $9.99 a month.

The obvious benefit for the networks is a big potential subscriber pool. Analysts estimate 44 million Americans subscribe to Amazon Prime -- currently 2 million more than Netflix -- though that’s not to say all 44 million watch video on the service. (As with other streaming services, Prime doesn’t release viewership numbers.) But Amazon also takes care of billing and any administrative bugbears, and networks don’t have to worry about building out their own streaming infrastructure. Albrecht said as much at an investor conference Tuesday morning, when talking about the decision to partner with Amazon rather than immediately enter the streaming marketplace with its own service: "You don't want to have to manage the marketing or customer service."

Consolidation, Consumer Convenience

Amazon is framing the program as a boon to consumers. “The way people watch TV is changing, and customers need an easier way to subscribe to and enjoy multiple streaming subscriptions,” Michael Paull, vice president of digital video at Amazon, said in a statement. Paull is speaking to the very real problem of subscription fatigue -- having to sign in to multiple apps or use multiple devices is a hassle that may prove too much of a turnoff for potential subscribers.

In essence, then, Amazon is just creating another pay-TV bundle, albeit one that’s delivered over the Internet instead of via cable. Vive le bundle.