HD Networks: How Much Carriage Is Enough?

Most of what I've been writing here lately touches either directly or indirectly with cable's struggle to stay bandwidth-competetive with its rivals. In doing that, I've been assuming that if they fail to keep up, they could end up with far fewer HD channels. But there's one thing that could prevent that. What if the lack of cable carriage keeps channels from launching in the first place? I touched on this possibility briefly in one of my first posts, but I think it deserves a bit more attention.

After all, cable is still the way most of America watches TV. HD isn't cheap, so if all the income streams (programming fees, ads, etc.) are going to be less, can you still make a viable business case from carriage on satellite, FIOS and whatever comes next? Or will the HD channel universe be constrained by what cable can carry?

I set up this AVS thread to explore the question, and got some interesting responses. Rick R points out that the channels exclusive to Dish can only be seen by 12% of TV homes. But he, as well as Fredfa and Cyclone GT, point out the "land grab" aspect, in which channels will want to get in early to stake out a position for a future in which current constaints do not apply.

NOTE: This post is ironically-timed for me, as my local Comcast just added MHD and gave NESN-HD its own channel (it had been sharing 882 with INHD2). But I think this subject will be of continuing interest, and much more so in 2007 when those new DirecTV birds go up and the "channel gap" widens.