For a 400m track; the race is only ended when one runner passes the other one.
Who do you think would be the best and how long would a race last?
Could a 800m specialist just gun it and try to put 200m on a slower runner in an all-in?
Would Kipchoge just slowly cook all opponents for 30k?
I'm guessing it would last around 5000m (depending of the opponents); probably entertaining, I wonder if that has ever been done.