Well, I can't speak to people who stopped watching football entirely over one guy. I still watched my team and other games as well. But I did not watch the 49ers anymore. I turned one of the Monday Night games off when the 49ers were playing and did something else. Colin did his little protest and I did mine. The 49ers sucked anyway so it wasn't much of a protest on my part admittedly.
Anyone who thinks this is just about one guy... Anyone who didn't at least reduce NFL viewing is a worthless excuse for a human being.
This is about the heart and soul of the NFL and about whether the NFL will move further to the Left. E.g. if the NFL didn't suffer a loss of viewers because of them letting CK use their stage for BLM protests, things like the NFL refusing to have Super Bowls in Red states would follow.