Do people think the decline of USA Dance membership reflects directly the participation in Ballroom dancing overall, or is it just a shift away from USA Dance itself in favor of other options, such as at dance studios, chains or independent?
Empirically, I see an aging Ballroom dance population that isn't replaced by younger generations, and dances that are much sparser than decades ago. I do believe most dancers are in a particular scene (Ballroom or other dance types) only some 3 to 5 years before moving on, so continually replenishing the ranks is always a challenge. Naturally, professionals have a big stake in helping do this, but amateurs really need to be motivated to bother.
OTOH, various dance instructors, in chains or independents, seem to indicate their businesses are booming. I do also know a few instructors who have left the business in the last few years, probably because they no longer can count on steady income.
There certainly are many more events, competitions or otherwise, Ballroom or other types (WCS, Salsa, etc.), but many events are far smaller than a decade ago. And there are certainly lot more instructors and studios than decades ago, but it's not clear to me how many are financially healthy.
So, what is the bigger picture of participation? The stability of the economy and jobs obviously plays into this.