Horse racing will not die in the forseeable future because it fills a niche in the gamblig economy. That simple. It will NEVER go back to preeminence either. It will most definately change, probably becoming a unified field with simulcast all over the place. Instead of dozens of tracks competing for customers you will have a few large companies that own various tracks. This is similar to what is happening to skiing, another non-growth industry.
I find it funny that you talk about horse racing like it is a game of skill and differs from slots in that it doesn't just take a players money. It does. A book will hold the theoetical 5% of the handle in sports. Variations of 1-3% off of this are not uncommon. Horses beats this hold % senseless.
Bookies hold around 20% of the handle in horses. This figure is not a fluke or a lucky hit. It is day in and day out. They pay track odds without the track expenses of a purse, upkeep and such things as salaries and promotions. If the maximum payout is capped then the hold increases dramatically. The parimutuel system is awesome for off shore since it takes track expenses into account when coming up with the payouts. Horses is a cash machine. The biggest problem is that there are not enough players to go around.
Most horse players are old guys who remember horses from their youth. They are junkies to put any sports player to shame. They will bet every race for one or two tracks. That means that a horse player will call his bookie 8-17 times a day just to place his bets. Most of these are small by sports standards, somewhere below $50, but if you get enough of them together 10-20 times a day it adds up quickly. I know of one guy that lost $32,000 to his bookie in a period of 8 months in 15 dollar bets.
The change in horse racing is driven by televised races and internet betting, not casinos with slot machines. A lot of people just sit at home, watching the races over the tube or through livecasts on the net. They will place their wagers and take care of all transactions from the comforts of home. The ones that go to OTB or to the track are looking for the same thing that sports-players look for when going to a stadium or to the local bar in order to watch a game... the company of their peers. Be it twenty guys screaming at a TV, forty thousand cursing out a ref or five thousand screaming "Run!" it is all the same.
Horse racing has at it's core a problem for todays' media machine: No heroes. Joe Schmuck doesn't identify with a four legged animal. And even when he can recognize the name of one of racings' stars he will only get to see him for a couple of years before the lucky bastard is put out to stud. Would Michael Jordan be as famous if he only played for three seasons? Would you know of Elway if he only threw for two? Longevity of career and success is a necesity for building heroes, an heroes is why we watch the game.
As for me, the christmas present I'm asking for is a large package full of guys who bet horses. I can retire off of them at my tender 25 years of age.