Advertisers will make a combination of changes. Some will pull NFL ads, and some will demand lower payments for ads no longer reaching previous numbers of viewers. Either way it will be less revenue going to the NFL.
I think the cable channels may also be noticing viewers like my brother. He does not turn to the channel showing an NFL game until at least ten minutes into the game - skipping any opening ceremonies, and the political antics going on with them. That can affect viewership of some ads placed at the beginning of the show.
I think the difference is accumulative: Once the “addictive habit” of “automatically” watching a TV game, of spending so many thousands for a in-stands game (plus the hours of driving there-parking-waiting-watching-waiting-leaving-driving back time required) are broken a little bit, the advantages and freedom of having time back will convince others.
Pappa Johns has already apologized to the NFL, doubt he will be pulling his ads. It is a weird situation, a liberal whines and companies fall over themselves trying to distance themselves from whatever was the offender. A conservative whines and companies shrug.
In gathering this data, the data that is reported is the 'Peak Viewers'. It looks like they gather data at 15 minute intervals, and then report that as the number of views in a game. Peak viewer's usually occur (from my reading the data) after the first quarter.
Only problem is less ads make football more watchable.