#Fire the NFL  -- and don't rehire them as soon as the owners relent.  Make management pay a price for not stamping this out day one!  The 'official' NFL Game Operations Manual states "The National Anthem must be played prior to every NFL game, and all players must be on the sideline for the National Anthem.
During the National Anthem, players on the field and bench area should stand at attention, face the flag, hold helmets in their left hand, and refrain from talking."

Enforce your very own rules!