That question is a very outlandish question, considering the greatness he has already achieved - I know. I know. I should have my head examined for even thinking such a thing.
However, read the question again, and then take a deep, deep look at his races.
Kipchoge has lost only one marathon race, and has never DNF'd. That alone to most people makes him the GOAT, but when you look at his times, I see a huge red flag.
Kipchoge has run 2:03 twice, with the majority of his marathon races being completed in 2:04 - He has run 2:04 five times. The 2:05s are not worth considering, because those times were acquired during the beginning stages of his marathon career.
The 2:04s ( as well as he 2:03 finishes) that he ran were races that were structured to go after the WR. The top pacers in the world were brought in for those races, to push Kipchoge (and other WR seekers) to break the WR. However, breaking the WR never came to fruition. And even though Kipchoge( and other runners) was on blazing WR pace, he appeared to back off in the last 4-6 miles of those races, to focus on getting the win - And that is the Red Flag that I aforementioned.
The Red Flag is that Kipchoge is unwilling to risk it all to break the WR. He plays it safe, so that his race is not compromised, where he gets beaten or falls prey to DNFing. He basically stops attacking to make sure that he gets the win. In Futbol, they call that anti-futbol ( Hi, France!), where a team goes up by one goal, but then stops attacking, because the team does not want to risk losing the game. They, basically, play it safe, or should I say they play scared.
Does Kipchoge run scared in the last 10k of his races? Does he fear the wheels will fall of if he pushes hard for the WR?
Let's take Wilson Kipsang's race against Bekele in the Berlin Marathon of 2016. Kipsang made a fast move within the last 6 mile of that race. He had to. Bekele is a massive kicker, and Wilson is a shuffler. So letting Bekele hang around until the last couple of miles of a marathon race would spell disaster for Kipsang each and every time, so that move was a no brainer. However, Kipsang went out way too fast, and his wheels slightly feel off, allowing Bekele to catch up. Bekele went on to win the race In 2:03:03 , the second fastest marathon time in history. Kipsang came in at 2:03:13, just 10 seconds off of Bekele. My theory is that Kipsang not only went after the win, but he also gunned for the WR. Had he put a cap on his speed, or even stayed back just a little, more than likely he would have won that race - But the point is , he went for it. Even though the win appeared to be in the bag, he wanted the WR , too. He took a shot. And considering he was the WR holder at one point, that was a ballsy move.
Look at Mary Keitany and the career of Haile G, to them, every race is/was a WR attempt. They are/were willing to red line to get the WR. We have seen MK blow up several times chasing the WR, and Haile G DNF'd four times in his marathon career going after the WR. Playing it safe was/is not a part of their mental make-up.
We got on Mo Farah for not really bleeding. He had tons of wins under his belt, but was complacent with just that. He made no WR attempts. And even though there is always talk about pacers going out at WR pace in Berlin and in London, we have yet to see Kipchoge truly chase the WR. So why should he get a pass?
Kipchoge is a great guy, humanitarian, and elder and leader in his village. He constantly talks about running a beautiful race, or that he is going to run a beautiful race. But his beautiful race does not = WR .
Is Kipchoge SCARED to take a shot, and if he is scared to take a shot, does that hurt his marathon legacy?
I would have to say YES.