Yes. This stuff was hugely unpopular last year when it was just a couple of guys doing it. I really think the NFL shot themselves in the foot here, and Trump is on the side that will eventually win out.
American football isn't destined to be the most popular sport in the US. Tastes change. I believe most of the popular support for the kneelers is among folks who don't really like football and won't start liking it, either. The opinions of their fans should be vastly more important to them than the opinions of the American people at large.