As of now there is no content, at least that I am aware of, except for to nature documentaries I saw advertised with the 4k TVs at Sears. And as for the price the ones I saw were still over $3000, but then again I've only seen the ones in the store and haven't really done research on 4k TVs.
I personally think that cable providers are dying out and will probably be gone soon. In my house we have roughly 400 channels, and I believe only two are watched; my parents watch NCIS and I watch Game of Thrones and Silicon Valley. If it were up to me I wouldn't have cable at all, the cost to watch ratio just isn't worth it.