Jakob will never break the 1500m outdoor world record. Here’s why:
1) the last 2 years his outdoor best has been 3:28.68 and 3:28.32 (in 2 time-trial type races, one of which being the Olympic final - the biggest race of his life). This is a possible sign his progression is slowing.
2) El Guerrouj ran his WR at the age of 23. Jacob has been training at the highest level at a much younger age than most, which may suggest he will reach his peak at an earlier age. He could take 1 second off his PR in the next 2 years (a significant improvement) and still be over a second off the WR!
3) Breaking multiple age-group WR’s is not a given that he will break senior outdoor records. Just shows that he started training seriously at a much younger age.
This is not taking anything away from Jacob and his career should not be seen as a failure if he does not break a senior outdoor world record. He will still go down as one of the best milers in history, but El G’s record is not easy hence why no one has gone near it even with the introduction of the new spikes.