By Daniel Kline Comcast, Charter, DirecTV, and Dish keep shrinking. That’s not the positive for consumers you think it is. The cable industry has lost roughly a quarter of its total audience since the end of 2016. So in six years companies including Comcast (CMCSA) – Get Free Report, Charter Communications (CHTR) – Get Free Report, DirecTV, and Dish Network (DISH) – Get Free Report have seen their subscriber bases shrink to 71.4 million at the end of the third quarter from 93.6 million, according to data from Leichtman Research Group. In reality, the picture actually looks a lot worse because …