William James Mayo was a prominent physician, and a co-founder of the Mayo Clinics in Rochester, Minnesota. He predicts that contagious and infectious diseases will be overcame, and a much more reliable food supply system developed (which is both the case, at least for the developed world). He remarkably accurately predicts much longer life expectancy (70 years again 77 in the US today) and also a range of the most widespread medical issues (cardiovascular deceases and cancer – he didn’t foresee diabetes, though).
He is one of the few who actually mention possible issues with possible military conflicts an ‘aggression’ in general (of course, no one could even imagine the World War II coming). Some of his references I don’t quite understand, for example “We point the finger of scorn at Russia (what for? for the Communistic ruling in general, or for the Stalinist regime in particular?) but tolerate Reno (?) and kindred subterfuges“.