The below article says that Kipchoge has said upfront that he won't be running again in 2018.
He also mentions a couple of times that he wants to break 2.
That raises a few questions then:
1. No Berlin? Why run London then? Surely he could just keep running London and Berlin until the conditions are ideal for a WR attempt?
2. Perhaps he wants to run sub-2 regardless of IAAF legitimacy more than he wants to break the WR. He probably knows that over time his WR would eventually be beaten anyway, but they can't take away being the first human to break 2. Also, maybe he wants to run the sub-2 now when he's probably at his strongest, then he can keep having a crack at the WR for the rest of his career?
3. Does this mean that there's another Breaking 2 attempt around the corner? Perhaps early next year? Then Kipchoge could break 2 and then set his sights on the Olympics the following year?
4. Does this give a chance for Rupp, Farah, Bekele to win Berlin?