Unfortunately, one of the inherent problems with horse racing and building a brand are the horses.
Hard to build a sport when the participants are gone shortly after you fall in love with them.
If they could get a commitment to run horses on a three-year cycle, they might have something, but good luck selling that to horse owners who crave that stud fee at the end of the rainbow.
You’d almost have to start a totally new thing. What if you took some lesser horses, but ones with more longevity and raced them once a month on a circuit? These horses would run for a few years before they cycle out. Familiarity could build some loyalty, but I imagine there’s myriad issues to make something like that happen.