Here's my solution!
Reduce the number of tracks. Eliminate year-round racing. Make each meet MEAN something.
Here's something else ... make trainers pick a jurisdiction to race at and allow them only ship for graded races (Derby, Preakness, Beldame, Woodward, whatever). Have a points system in place so that divisional champions are in place. Hash it out in a playoff style format. End it at the Breeders' Cup.
Trainers would not be able have mega-stables since they couldn't have strings in California, Kentucky, and New York. This means the horse population would be spread out to other capable trainers who seldom get a "big horse." Steve Asmussen can't stable 300 horses under his name at one track, so those athletes would wind up in other hands. This also gives the sport more possibility at finding other names outside the Top 10. It could also reduce, over time, the number of racing horses making for a better racing product. This would anger breeders, but the junior varsity has GOT to go.
As for those pushed to the margins, real, real small trainers and horses? The trainers will either have to go to work for somebody else or find a new job. The marginalized horses will need homes, and maybe through a subsidized program, marginalized trainers can help care for the excess horse flesh that would result in this systemic overhaul. If Suffolk Downs closes, try to hold onto the land as a retirement park. Try.
Did that make any sense? If not, well, I'm sorry. There, I said it.