The early results are in and they do not bode well for the NFL:
Despite two teams with big national followings, SNF snared a 4.7 in early ratings among adults 18-49 and 14.81 million viewers last night. In numbers certain to change, that’s a fall of 28% in the demo and a hard decline of 23% in sets of eyeballs from the early numbers of the the September 8, 2019 SNF season debut.
More precisely, the decline was from a 7.5 rating among 18-49 and 22.21 million viewers... of a game that New England beat Pittsburgh 33-3. That's a loss of up to 7.4 million viewers.