Good points. While he is ‘only’ 1:40 off, that’s a lot of time to take out in reality.
Saw the female world record was set this weekend as well at Chicago. @cander49 has now run two races where a wr was set, so he must be the X factor. 
Hahaha. I had a fairly mediocre day in Chicago this year, but at least I was only 1:53 off my PR with a rough second half and a decent bit of late race puking. Motivated for next time. I think my diet is holding me back right now, so I'm going to clean it up and cut all the ridiculous junk food that I eat.
There should be zero doubt that Brigid Kosgei is doped to the gills. She's in the Gabriele Rosa group, for which many of the previous world beaters have test positive and get banned (Asbel Kiprop won 4 combined Olympic or World Championships gold medals on the track, Jemima Sumgong won an Olympic gold and the London Marathon, Rita Jeptoo won the Chicago Marathon twice and Boston three times). Sadly, Rosa also coached some big talent before all the bans that must all be heavily suspected for doping, such as Paul Tergat (former marathon WR), Martin Lel (winner of NYC and London Marathons), and Moses Tanui (world champion at 10,000 and two-time winner of Boston Marathon). Rosa, himself, was charged with doping his athletes in Kenya, but the case was eventually dropped.
I'm not that excited about Kipchoge's sub 2, to be honest. There wasn't really a doubt he could do it with that kind of pacing. Based on how easy it looked for him and how much he sped up in the last kilometer, he could have run 1:58:xx under those conditions. I've argued repeatedly that he was capable of 2:00:xx in Berlin last year with perfect conditions and pacing. It was slightly too hot and sunny (not a big deal, but worth probably 20-30 seconds, and his pacers did a terrible job, pacing a little unevenly and dropping earlier than they were supposed to. It seems possible that someone could organize a real race with a bunch of 2:03 guys getting paid a bunch of money to pace in that Vienna formation as long as they could hang on (25k at least?), and then he could just finish on his own. The race would be legal without having subbed in pacers, and he'd have a legitimate shot at sub-2 in a real race. The other main issue is that he's not, on paper, clearly the top marathoner in the world anymore, so it's less special given that Kenenisa Bekele could almost certainly have done it as well. Bekele is back within 2 seconds in a real race (2:01:41 in Berlin recently), and he did that coming off an injury with an abridged training cycle. Bekele beat Kipchoge on the track nearly every time back in the day, and he's running essentially the same time as Kipchoge without having enough time to be 100%. Dude was a full 30 pounds over race weight earlier this year after injury, took it off in two months, and came back to run a 2:01. If he stays healthy (a big if at this point in his career), there's no doubt he is capable of at least sub-2:01 under legal racing if the conditions are good. Ultimately, Kipchoge will always have a big asterisk on the 1:59, and it will steal the thunder from whoever does it under a legal scenario, which is too bad for them.