Horse population peaked? So what? That assumes the population number is an indicator on their quality of life. However, as the allegory indicates, a horse's quality of life today is leagues better than what it once was. Better feed, better health care. A good barn is a harder to come by, but what "good barn" means is a raising bar by the day. Pretty good odds of making it into your late 20's.

There's fewer horses now, but it's not like they were taken en masse out back and shot in the head (though that certainly happened to some). They just aren't bred as much. I don't think anyone (horses included) bemoan that.

If horses are the comparison, then I don't think humans have a thing to worry about.