With good results coming in from its product trials in Boston and Chicago, Comcast has decided to roll out a low-cost "skinny bundle" TV service across the country in the third quarter of 2017 rebranded as Xfinity Instant TV.

The monthly charge will be as low as $15 for an offering of local TV channels, HBO, plus cloud-based DVR storage of 20 hours, sources close to the project confirmed. That's $5 less than the lowest cost Sling TV bundle offered by Dish, the current category leader with about two million subscribers, and $15 to $20 under the lowest cost deals from Sony's PlayStation Vue and the forthcoming YouTube TV.

Originally called Xfinity Stream, the new Instant product is distinct in other ways, as well.

For one, Xfinity Instant TV is focused particularly and exclusively on Comcast Xfinity customers who are signed up for high-speed internet service but not taking a TV option. The company hopes that once lured into the TV-viewing fold, customers will eventually opt for a full-fledged video-subscription package. Comcast previously tested and found validity in such a relationship-building experience with a bargain "dual-play" option called Internet Plus that combined high-speed internet with a minimalist cable package.

Also, while Xfinity Instant TV is delivered through the customer's internet-service gateway/modem, it is piped through the same private, internet protocol managed network that Comcast now deploys to deliver cable channels to its set-top boxes, rather than using the public internet network that's relied upon by rivals, which includes the hugely popular "on-demand"  movie/TV services Netflix, Hulu, and Amazon Instant Video.

As a consequence, even the heaviest of Xfinity Instant TV users won't ever have to worry about exceeding their internet data-service caps, a possible concern with other streaming TV services.

Geared to a mobile-first customer, the Xfinity Stream trials have had early adopters sign up online, download the app, and then start streaming across computers, tablets, and phones. With the product's evolution, options will grow. To watch on big screens, Xfinity Instant TV customers will be able to tune in through the Xfinity TV app on Roku streaming-media boxes, which connect to TV sets. And as with skinny bundles, customers lured by that bargain $15 offering will be able to upgrade services, with a larger $40 bundle and specialty packs of channels (costing around $5 to $10 each) that are fine-tuned for kids, movies, sports, news, lifestyle, Spanish language content, and more.