hCaptcha makes money by having humans label things to teach machines. This suggests that at some point, the machines will be nearly as good as the humans at labeling. At this point, until the humans are tasked with a different training exercise, a bot will be effectively indistinguishable from a human via hCaptcha.
If there's value in it, it sounds like a spammer could train an hCaptcha-defeating bot via hCaptcha.