The artist seems to guess that people thirty-six years in the future would adopt a look that was a cross between Native American and ancient Greek.
The couple might almost get away with dressing like that in a museum now - they definitely would get away with dressing like that on the street in NYC in 2017. And the guy's tattoos are definitely a 21st century touch, although it's funny that the artist changed so much else but the guy in "1950" is still holding a cane.
I had guessed that the artist Otho Cushing was gay by the way he lovingly renders the butt and biceps of the 1950 guy, and sure enough, although the Wikipedia article doesn't explicitly say Cushing's preference in the main body of the entry, at the bottom it indicates that one of the categories the subject falls under is "gay artists."
Also this other drawing by Cushing.