I know it would cost more, which is why it'll never happen. But I also think it would be well within the NFL's budget to handle it. If they can do it for MLB they can do it for NFL.
It helps now that the Lions are better. But I'm sure we all clearly remember the years when the Lions were the red-headed step-child that no one cared about and we'd get the same cliched stories (did you know that Stafford and Kershaw were on the same team in highschool?!?!?), wrong names, and bad information from the announcers, etc.
I don't want the announcers to be complete homers, but I also wouldn't mind a Detroit focused announcer team who'll at least have accurate information about the players I care about and won't repeat the sale old tired crap all the time.