* Have Exclusive, Attractive, Programming
A good example of this is Spike TV. On neither Shomi nor Netflix will you find Bellator, Glory, Cops, Lip Sync Battle, Jail, or certain cards from Premiere Boxing Champions. Since I like watching all of this, I'm gonna stick around.
* Niche is Nice
Unlike Teletoon, the animation on Cartoon Network is much more appealing to adults. Compare the likes of Adventure Time, Regular Show, Gumball, and Steven Universe, to most originals from Teletoon and YTV. If you wanna know the appeal behind Japanese animation, Cartoon Network's original shows are your best bet.
Although, it would be nice if Adult Swim aired more of their originals. But that's what you get when your interpretation of the brand is "adult animation" as opposed to "FOX cartoons and live-action comedies". I mean, isn't that what TBS is for?
* Serve the Underserved
Wanna know why FEVA TV is better than BET's Canadian feed? Then read the posts I've made; I've already said my peace.
At the moment, excluding broadcast networks, these are the only channels I'd want to subscribe to. These are the networks and brands that appeal to me the most and, therefore, are worth sticking with cable. Different people have different tastes though, and there's no guaranteed that enough people share my interests enough to subscribe to these channels as well.
You can guarantee that most people will stick with Showcase, CP24, YTV, Treehouse or the sports channels and American networks, but not on crappy lifestyle networks or the likes of M3, Fashion Television, BookTelevision, G4, MTV2, DTOUR, or even DejaView.
...Different tastes, remember?