The Sports Broadcasting Act of 1961 made it illegal to broadcast
a game within 75 miles of a high school football or college football game taking place at the same time.
Link
More specifically, the
SBA's allowances don't apply if a game kicks off on Friday night or Saturday "during the period beginning on the second Friday of September and the second Saturday of December in any year from any telecasting station located within seventy-five miles of the game site of any intercollegiate or interscholastic football contest scheduled to be played on such a date." Link
So the bottom line is that the NFL is free to broadcast super early (like this Sept 6 game), or late season (like we have seen for years. They probably won't expand Friday night coverage because television ratings are not usually very game on that night - people go out after work, or it's date night, and the west coast audiencee is still at work. But since it's week one, fans will make an exception in order to finally watch NFL football again.