Hi Dan. That is actually not true. They are prohibited by law to broadcast games by law. Sounds crazy, right? But it is true. It was put in place back when the NFL was given an anti-trust exemption so that the teams could collectively bargain for a TV rights package. Congress didn't want the NFL to compete with amateur football, so they can't broadcast on Friday's during HS season either.
Having said that, there is a belief that the law only pertains to broadcasts controlled by the FCC. And streaming is not controlled by the FCC (at least not at this time). The first test is the Black Friday streaming only broadcast. There will be more. It will slowly evolve to the point where the NFL is playing on Saturdays and probably some Fridays as well.