re: What is the end goal to taking the knee during the national anthem?

Taking a knee was slowly fading away until Trump called NFL players SOB's. The reason for kneeling than seemed to switch from a protest against inequality, to a group deciding this is their way to show a form of unification. Ultimately Trump attacked their character and naturally one would expect them to take offense. Kneeling for the anthem may very well hurt the NFL financially, but as a group (owners, coaches, players, etc.), they will not let an outsider attack them.