Fair question. For my part, after having full and part ownership a few years ago in four horses (one was a stakes winner), I have no intertest in owning considering the current state of racing. For the most part, current ownership at the medium to top level is by "old" racing money. I haven't done a statistical review of the ownership of the past 5 years of graded race winners, (nor do I have a lot time to do so) but if you do, I think you will find my statement will bare that out.
Here is a link from the Jockey Club showing the foal crop stats for the past 18 years:
http://www.jockeyclub.com/default.asp?section=FB&area=2 . In the US it's down 51%, down 57% in Canada and down 67% in Puerto Rico. I'm sure if you were to check other countries, you would find similar numbers. I think that is an indication that new ownership is sparse and there is less and less interest in breeding and subsequently racing ownership, except by "old" money. I think you would also find that it is the 50+ yrs olds and older who are responsible for the majority each track's handle.
Additionally, I talk to a lot of people in and out of racing (though have some interest) here in the US, Australia, and New Zealand and the sentiment from my conversations support what I stated about new fans coming into the game (Ownership or punting).
Concerning fan base, I'm sure you could go to any track in the US and see that attendence figures are way down. Perhaps the exception here is the small fair meets that run for a couple of weekends a year. People have a day out to enjoy the excitment, so perhaps there is hope there.
Of course overseas attendence is still good as many countries still see horse racing as a sport with entertainment value verses a mechanism for gambling.
Every year we get this great platform in the Derby/TC and the BC where we get the spotlight and cannot build on it. Then we have the outcome in the Derby that many of the casual observers will see as unjust, will walk away thinking, what kind of a "clown show" is racing when the winner (fastest horse) in not declared the winner. Subsequently, they don't return or go to their local track (if there is one) to allow whatever interest they may have had in racing grow.
As far as horses regaining their momentum, maybe/maybe not. I've seen 2 and 3 mile hurdle/steeplecase races (horses who have expended way more effort) and see horses regain/re-rally to win. Concerning the Derby, they still had 2 furlongs left to race and from my perspective, once they all straighten up at the top of the stretch, none of them had an excuse for not going by MS. Also, keep in mind that MS also lost momentum by not getting a hold of the track/the bump with the #1, but once all straighten up, it was "game on" and MS was easily the best.