I suspect that the new football league would not allow Kaep to take a knee.
Supposedly their were NFL teams willing to sign him if he would agree to stop doing it. He refused.
According to the Washington Post of San Jose in the East Bay (sometimes known as the East Bay Times), the XFL, Vincent McMahon's league that's coming back next year, Copper-Nickel was approached to play there. HOWEVER, his contract would require no kneeling or any of his other foolish behaviors.
And the terms are non-negotiable, according to the article. If you aren't willing to accept the rules, don't let the door hit you on the way out!