David Rudisha- Clearly not in shape at the moment, but another year might give him the necessary time to drop weight and gain the speed endurance to get through multiple 800 rounds.
Galen Rupp- Gets another year of building back from his surgery.
Elijah Manango- Same as Rupp
Jakob Ingebrigtsen- Can build back from injury
Castor Semenya- Needs as much time as possible if she wants to build strength and speed for 200.
Nick Willis- This one's a bit tricky. He's 36 so the clock is ticking, but clearly needs to improve his fitness at the moment.
Mo Farah- Can focus on building finishing speed for 10km (although it sounds like the race would be anything but a sick and kick).
Rudisha. I do not think so. Rupp. Rupp is naturally a 10000m man but I do not think he has it in him to race final 800m sub-1:54 anymore. Jakob Ing. Maybe. Semenya. Sprinting is like ballet and hitting a baseball. The necessary neuromuscular coordination to sprint fast must be started very young. Semenya has been doing a lot of 200m, 300m & 400m repeats over the past ten to fifteen years. It's not the same as doing 50s & 150s, working on start, sprint coordination drills and film study (studying one's sprinting form in super slow mo). Semenya possibly could have been a sub-22 200m athlete if Semenya started sprint training very young. No sub-22 200m this year or next year for Semenya. If Semenya thought Semenya was ever a sub-22 200m athlete, Semenya would have focused on 200m a long time ago.