I would like to see what other world class sprinters could run in the 40, people who could accelerate faster than Usain.
Usain was fast in the 100m because he reached his max speed around 50m and could sustain it for nearly 40m. Most other sprinters could only sustain their top speed for 30m. So while others are starting to slow down, Usain was still able to maintain max speed.
Somebody like Mo Green, Gatlin, or a new sprinter to keep your eye on, Christian Coleman, would likely have faster 40’s than Usain.