Will Big Cable become the next big distributor for Internet video? I’m not holding my breath.

Comcast, just as the pay-TV industry may be hitting an irreversible decline in subscribers, is gearing up to launch what’s currently being called “Watchable”: a multiplatform outlet to serve up shortform videos from partners on TV via set-tops, mobile apps and the Web. Publishers in the mix are said to include Buzzfeed, Vox Media (in which Comcast’s NBCUniversal has invested $200 million), AwesomenessTV, Vice Media, the Onion and Fullscreen.

The cable giant sees an opportunity to reap ad dollars by aggregating audiences for digitally produced content — not only from its (shrinking) traditional cable TV base of 22-plus million users, but also from non-subscribers.

But will it work?

Comcast’s strategy here looks like a defensive move — an attempt to offset lost video-advertising eyeballs as TV viewing declines, especially among younger consumers. And that points to the real problem Comcast will have in building Watchable.com (a domain name the MSO registered several years ago) into a brand that rivals the heft of YouTube or Facebook: Online video is a less attractive business than the old-fashioned cable TV bundle, which has generated kabillions in revenue and fat margins over the years.

The gears of cable’s technology machinery grind slowly, and so it has been with Comcast’s Internet-video efforts, which date back nearly a decade. Comcast leads MSO peers in trying to bridge the gap with the digital-video world, as a first mover on TV Everywhere and with the rollout of the X1 modern TV guide. Still, neither Comcast nor any other traditional pay-TV provider has been able — or eager to — punch up Web video in a serious way.

Now comes Comcast’s Watchable project. And you should expect to see its mixed feelings on display in terms of how this service is packaged, marketed and designed — basically, as a supplement to “real” TV, which is actually paying the freight.

Comcast’s reluctance to plunge quickly into Internet video, despite the sector’s massive growth, shows that it doesn’t want to hasten the decline of TV by siphoning away viewers to entertainment options that produce less revenue. Indeed, part of the strategic rationale for Watchable is classic Big Cable thinking: By pumping more content into the TV bundle (in this case, Web video) available to users on their big-screen TVs, they’ll be less likely to cancel or downgrade their pay-TV plans. Note that Comcast’s supposed Netflix rival, Streampix, is now really just a retention/upsell tool for the core cable TV biz.

To attract content partners, Comcast is offering a 70% share of video-ad revenue generated by Watchable, the Wall Street Journal reported. That’s a bigger cut than YouTube and Facebook, which each keep 45% of the pie. Sure, Comcast needs to woo content suppliers with better terms than the heavyweights, given that it’s a new entrant crafting a digital brand from scratch (like Jason Kilar’s Vessel, which also offers partners 70% of ad revenue). But the 70-30 split also indicates Comcast’s priority will be trying to gain traction rather than realize profits.

Is Comcast in it to win it as a digital-video player? It seems like a hedge, rather than a sizable new line of business in the way Facebook’s video push is unfolding. And it’s also less ambitious than the over-the-top bets from other pay-TV operators, such as Dish Network’s Sling TV and Verizon’s forthcoming mobile-centric Go90 service; those are more explicitly banking on the rise of OTT despite the risk that their legacy customers will trade down to cheaper Internet packages. (Comcast’s new Xfinity Stream, priced at $15 per month with HBO and broadcast TV, is available only to customers who also take its broadband service.)

All that said, Comcast has no choice but to plant a bigger OTT flag of some kind in the turf. The question is whether it’s going to be too little, too late.