The race's setup is horse-friendly as well: Shorter than a regular marathon by a few miles and on flat terrain. A longer distance on hillier terrain would be won by humans much more often.
There was an interesting article a couple of years back, positing that the years that humans won coincide with unusually warm weather.
The takeaway was the humans have a superior cooling system for efficient long distance running, compared to most animal's superior sprinting capabilities.
'AI' is not an adversary. It is simply a tool created by hundreds of humans coming together.
It's like watching 1-v-100 boxing match. Of course the 100 are going to win.
Enjoyable sport has always been about ~similarly matched opponents. When we have DeepMind AI Go vs. MindDeep AI Go, that's when things get interesting.
You have to remember the specific comparison and the art that humans tried to partake in to master go.
Humans do not run to beat horses. We never compete. That would be silly.
Cars and humans also do not compete at the 100 meter dash.
If humans and robots compete at 100 meter dash than the olympics will similarly lose its luster.