Here's my take.... If this keeps up there's only two possible answers.... The leagues will make it mandatory for players and personnel to stand. Or the leagues will drop the Natl Anthem from their pregame ceremonies.
Whatever the easier route proves to be.
Yes, there would be a PR hit from dropping the Natl Anthem. But there's already a PR hit with it being used and abused the way it currently is. And that is a long term problem. First it's growing and spreading for this current issue among leagues and players. And now that the door has been unlocked, there will be other issues down the road that will elicit this same protest. And probably of less importance too now that not standing or kneeling has become the new normal. At some point we won't even know what they are protesting exactly because it could the current issue, a new national issue, or even a local or personal issue.
Meanwhile, doing away with the Anthem entirely is a short term problem. It'll hit hard and fast but then fade until not playing the Anthem before games becomes the new normal.
Because businesses don't need their employees protesting on company time, and especially not when it harms the company. And if it continues, they WILL put a stop to it one way or the other....