Maybe not impossible, but I seriously doubt it's viable in the U.S. at least.
The cost for even getting a lowly runt of a cable channel operation is beyond the scale of the "willing to pay" pool community. The pricing is large, where licensing money goes tothe event producers, the video production company, a cable distributor, and the final cable companies... And there is probably much more on top of that.
Each one of the above wants a piece of the pie, and now you haven't actually filmed anything yet. For the existing video you'd have to go to each producer and rights holder and gain approval and negotiate for the initial licensing option payment, and ongoing revenue. If they have exisitng licensing agreements that preclude them from licensing to you then you're SOL anyway.
Finally, if you don't have about 1,000,000-plus viewers (old number, probably different now) to subscribe then good luck. It may be possible to have a smaller viewership and exist in a micro-market. The Cartoon Network started with a micro small viewership (still bigger than pool could bring in the US) and survived, but I don't see the general population buying into a pool channel in the US, and I don't see the fine citizens (by fine I mean cheap) of AZ billiards doing so either... Heck it's hard to get people to pay $10 to watch a convenient pool stream for a prime tournament that may come along once a year.
I think the future for pool is the online stream. We now can get more pool via online stream than we ever got from ESPN. Maybe one day Amazon and/or Netflix will start providing such a structured alternative streaming video service which would be similar to or rival "standard" cable (both have that goal), and that it would prove to be a good venue for the existing streaming pool producers to show their conent through. Or maybe Ustream will step up to the plate with professional production quality offerings, which I am sure they would love to do.
Be it Amazon, Netflix, Ustream, or whatever, if pool video producers want to show their stuff they will need to invest in better production quality. That investment equates to higher cost, and that means a lot of viewers are needed.
All that being said, a few years ago I read about a cable station in Japan that was going to have 24x7 broadcasting of pool. I wonder how that went?