NY TIMES article cites league contemplating elimination of commercial breaks, altering ad schedules, reeling in referees and modifying clock rules to keep action moving.
First real acknowledgment of the real trouble league viewership is in, cites decline of 35 percent nationally in prime time TV viewership since 08, thou claims overall league viewership up...but doesn't break down if that's gross growth or per game.
The commercial problem didn't start until Fox won NFL rights in 1994. When they started broadcasting games the amount of commercial breaks increased greatly.