Consider the Browns, who left Saint Louis, a baseball town, for Baltimore. All these years later, Baltimore is the number 29 TV market.
The Chronicle article suggested that Fisher wants to take the TV contract from Oakland. Sacramento is a bit more than 80 miles, or an hour-and-a-half, from the Bay Area. The drive is all on I-80. I don't remember much surburb or urb to fill in that 80 mile gap, while the Bay Area population spreads more heavily down the peninsula toward San Jose.
It's very populated along I-80 through Fairfield, Vacaville, Dixon, and Davis. There's maybe a 5 mile gap between Davis and West Sac due to lowlands and flooding risk, but Solano and Yolo Counties between the East Bay and Sac have about 800k people on their own, and they get Kings games on NBC Sports California while the immediate Bay Area gets infomercials during those games. But I actually became a Sacramento Kings fan when I lived 30 miles from SF and 70 from Sac because it was an easy drive outside of rush hour and tickets were much cheaper than for the Warriors.
Re: media market, the A's have had terrible ratings for years because the Giants own the entire media market, including much of the East Bay. While per subscriber fees might drop, ratings could actually be higher after the move, and ad revenue will likely increase.
I live in San Jose now, but will probably attend some games in Sac, I hate going to Oakland, the stadium really is that bad and the city is a dump. I'm glad they're moving.