Cable operators and Satellite are competing with each other, not with OTA users.
Cable is not everywhere, there are still plenty of rural areas not serviced by cable. Satellite technically is everywhere, but again there are limitations based on the direction a dish has to point, and even in some cases bylaws in condo communities restricting owners from using dishes. So OTA is and will likely be for a long time something necessary to ensure your channel(s) are getting out to as many people as possible. That is what the advertisers want and in the end they are the one's paying the bill.
Also keep in mind that the number of people "cutting the cord" is relatively small. New condos and home developments are growing everywhere you look, and those are plenty of new subscribers.
Now when we start to see better and easier ways to access content on line, thats when cable and satellite companies need to start to take notice. And it's already here for the techy types, just not ready for prime time yet. Apple TV is just a teaser of whats to come.