I was in Rio last week. I can guarantee you that sub 2:07 in that course it's IMPOSSIBLE. Even for Eliud Kipchoge.
I jogged over the official circuit (over Bahia de Guanabara, for example) in the morning, and I know, I'm not Kipchoge, and relative humidity in May it's higher than August.
But expect a race with something in the mid 70's (even low 80's after 35k). over 70% humidity, 22/23°C dew point., and high pollution, of course.
I don't know if Wesley Korir is in shape. But forget about leaders cruising the half in sub 1:03. That would be suicidal. Expect something in the 1:04.10 at least.
This is a course (prima facie) for athletes like Ruggero Pertile, Meb Keflezighi, Wesley Korir (if he's in good shape), Eritrean Geb, Marilson, and Stephen Kiprotich.
I don't know about Ethiopians, but they can make a big mistake if they put Dubai top 3 athletes instead of Kenenisa Bekele. This is not Dubai. 2:04/2:05 in Dubai it's not even 2:08 in Rio.