A 30% drop may not seem like much, but this is catastrophically bad news for an organization like Susan G. Komen, which needs every penny it takes in. The overhead for this charity is fairly high--it costs money to pay severance packages for those disgraced and incompetent leaders, you know. Their whole plan was to increase participation by severing ties with Planned Parenthood; that has blown up in their faces. These numbers are devastating. You cannot sustain a charity with dwindling enthusiasm and declining participation. Corporate sponsors will take note of this and vote with their feet. No one wants to back a loser, and no one wants to put their name on something where the turnout drops like this.
This organization has begun to see the effects of what it accomplished by angering the people who have dedicated themselves to supporting it. Aside from a name change, a restructuring, and a dedicated commitment to supporting Planned Parenthood, I don't know what could reverse this trend.
And yes. This is a trend; as dedicated volunteers fall away, the links to the communities where these events are held fall away as well. A drop in participation means that it is possible that those who did turn up will look at the fact that their neighbors didn't show up and will turn their backs on Susan G. Komen as well.