same thing has been going on with sports for years now--overall, annual decline from the year previous, for every league. (well, maybe not the NFL because they strictly guard their content)
the youngers tend to watch everything online, and generally highlights after the fact. That especially seems to be the case in the NBA. People just absorb content different now, and 75+ year old systems are completely blind to it.
btw, I didn't watch any of the DNC. I have absolutely zero interest. The problem in this country is beyond obvious at this point, and it has been for nearly 20 years with zero ambiguity.