For NBC, this means there will be weeks where they have two full nights of football, a night of The Voice, and an additional hour of The Voice, along with an hour of Dateline. That's 11 unscripted hours. Add 4 Dick Wolf shows into the equation (5 if there's a Chicago Law on in the fall), meaning only 4 hours left to be filled.
For CBS, it most likely means that The Big Bang Theory will play musical chairs yet again and air Monday at 8 some weeks, leading into a comedy at 8:30 when there's football, and a two-hour comedy block on Thursday when there isn't.