I raced almost 40 times last year. It was obvious the numbers were down a lot. A couple race directors were really happy they stayed level. I also saw a handful of small races just cancel because nobody was registering. I saw results of races having between 5 and 15 finishers. Those won't be around next year.
Another trend I saw the last few years was runners going to trail races. I did a lot of trail racing in 2012 and a handful in 13 and 14. This year practically every trail race I looked at is sold out because they are only allowed small numbers (250) so as to not damage the trails. There haven't been many new races to supply the demand probably because the profit potential is small and it is hard to get permits, etc. With that occurring, you are left with a 5k every weekend or paying 75+ for a small half marathon.
Another trend I am seeing that is a real turnoff from a race is graduated fees where the cost may be $50 6 months ago but $100 the week of the race. I got 3 e-mails in one day telling me prices for their race was going up and the races were 4 to 6 months away. Rather than hurry to register, I crossed them off my list of races.
These trends all make running less appealing to everybody and younger runners more so because they don't have as much expendable income and tend not to plan activities far in advance.
The last point is that racing had a nice increase when the economy tanked. People still had money, more time to train and race and race fees hadn't spiked up yet. It still only cost a couple bucks more to register day of race. With the rebound in the economy and the sometimes extreme price hikes, it is no wonder a lot of races are getting smaller..