Mo has not done anything to suggest he will win London. (The race is stacked.) If the race is slow, I guess he has a shot, but that's unlikely. There are a lot of athletes with faster track and road performances than Mo who never made a dent in any of the WMMs. The top marathoners are now specialists, gone are the days of track guys like Geb or Tergat winning marathons. I can see Mo debuting in a respectable 2:05 and perhaps getting down to 2:04 is his 2nd or 3rd marathon and maybe even 2:03 when steps away from the track.
Ironically, the way Mo has won races and his 1500 PR last year suggest he is fine tuned for speed and I not sure he can get all of that out of system in 6 months. Evans Rutto has the fastest marathon debut in 2:05, but he was a road race specialist when he ran his first marathon. I think Mo can eventually challenge for a WMM victory when leaves the track, get a full year at HA running close 200mpw is his system. AlSal is a great coach, but he can't produce a great marathoners until he gets an athletes who starts focusing on the marathon while they are still young. Some of the top Africans are now running marathons in their their teens and skipping the track.