If the league is smart, the owners will vote next week (or whenever it is) to make players stand for the anthem. Not standing falls under "conduct detrimental to the league" so any player that whines about it can go suck it. If Rog can fine someone for wearing shoes that honor a national hero or some other nonsense, then he can fine them for not standing.
I doubt they will force anything out of fear of being called racists.
This whole thing should be laid at Goodell's feet for not enforcing the rule in the first place, another example of his consistent inconsistencies. He should be fired for letting it get out of hand but of course that won't happen either.