Horses were domesticated between 3500 and 2000 BCE. The probability they could have been domesticated 10 000 years before in America is quite low
The fact is, we don't have any evidence for or against any domestication, or wheels, in North America. Any evidence that might have existed was burned up along with everything else, in the YD conflagration. So, any estimation of probability is 100% guessing, with a decorative and misleading frosting of "science".
What we do have firm evidence for is domestication of tree species in South America before 10,000 years ago. So, domestication did happen there before similar events in Eurasia.