My great-great-great-great-great-great-grandchildren will have been dead 100 years before there is any serious fixed odds for harness racing. It has been tried. E-horse had E-horseX. It was styled after BetFair. There was ZERO market. A few people tried to be market makers, but the action was typically less than 100 for all horses combined. That was 20+ years ago, when harness racing actually had a spot in the world of sport. Since then, the interest has dwindled and I find myself increasingly less sad with each track closure.
It was pointed out that people will always buy horses. That is only true to the extent that purses remain slot infused. If that were to dry up tomorrow, the sales would see drastic reductions, and within a few years, I'm guessing we'd be looking at levels around 10-25% of current.
The real key to create a bet-able sport, is to make it competitive and interesting. Harness racing seems hell bent on making it uncompetitive, and it sure as hell isn't interesting to anyone not already in love with it.
And, does winning with the rebate/discount/bonus count? If so, I might argue it can be beat.