I don't think USBC is all that worried about getting the 80% back you're talking about. It's trying to generate interest and bring in newcomers, and they think that can be accomplished by building up the youth, high school, and collegiate programs, which it has done/is doing, and by making the sport visible (i.e. Olympics, PWBA, PBA, ITC's, ISC's, etc.) While they would gladly welcome the defectors back with open arms, I don't think they're trying to bring back the old guard; I think they're trying to bring in the new recruits.