As long as they can get their locals via the antenna, it could work..
But any service without the networks, has never been able to receive mass market penetration, for example, you brought up sling, even at it's lower price of around $40, highest # of subscribers was 2.69M, now at 2M, Philo, at it's price of under $30, at about 1 Million subs.
Yet YTTV, who has the networks, has 8 Million subs, at a more expensive price of $73.