This is interesting, thanks for sharing!
I'm not surprised by the RnR... They had such a huge growth rate, and have enough detractors, that at some point there was bound to happen. Interesting seeing the broader top 25 trends.
I have noticed a decrease in folks running for the charity bibs. I know last year NYCM had lots of bibs available far later in the year than usual... there's a point where folks do other things to raise funds. Ice bucket challenge takes a lot less training... And after the Team in Training model (I make a donation and you get a free race, hotel, etc?) got negative publicity, it seems they are represented at fewer races too.
All this said, perhaps the marathon is reverting back to the runners/racers and fewer hobby joggers/bucket listers? Or at least those who are doing it are running Disney, which acutally makes a ton of sense!?