I think that even rare disease diagnosis can be done better by algorithms by using Isabel healthcare's diagnostic system[1] or Watson(in the future).
The place where a human will contribute the most is the interpersonal stuff:motivating people, digging data from people(although computers compete there[2]) and administering placebo.
And of course doing the physical stuff.
But that seems very different from the job of a doctor and closer to the job of a nurse.
[1]http://www.isabelhealthcare.com/home/default [2]There was some research that showed that people give more personal information to a computed form than via face to face chat with a doc.