You and most people are falling into the trap of thinking that this is a normal marathon like berlin or london and using those times as a reference. It isn't. This is an optimized time trial of the likes we have never seen in professional marathoning. We have a pretty optimal course. We have a phalanx of pacers. There will be no tactics. Who the heck knows what a fast marathon in those conditions in.
And yeah maybe Nike has come up with shoes that make you 2% faster which isn't out of the realm of possibility. And before you call them cheating shoes, how much faster do you think the average 2017 spike track shoe is compared to one from say 1917?
I have no clue what the odds are. I am guessing nike has a lot better numbers (i.e. maybe they have measure kipchoge under normal circumenstance versus aided and his lactate/hr/... are low enough to suggest that running 3% faster is possible ).
I just hope they have good weather and pacing and really go for it. I want to see them hit 18 miles at 2 hour pace (A 58:30 HM should be able to run that and I expect kipchoge could do that if he peaked for a race) as see what happens. I don't want to see some 2:02 race from them running 61/61:)