His wife and "life spirals" partner died in 2017 at the age of 81. They had continued to skate until at least 2015.
I had the pleasure of seeing them skate in Lake Placid some years ago and they were often in the audience for any skating competitions held there.
From Skate Guard Blog on X (formerly Twitter)
Skate Guard (Ryan Stevens) also quoted from a 2004 essay that Oleg wrote :2X Olympic Gold Medallist & 4X World Champion Oleg Protopopov sadly passed away yesterday at the age of 91. Oleg was not only a brilliant skater - he was passionate about bettering the sport.
"Let them to create independently (without ISU standards) new fresh innovative movements, combinations, elements & they will do their best according to the personal abilities, because it will be the best motivation to work."
"The nature of a skater from the very beginning is an artist. Remember American Jackson Haines who was the first in the World to skate - backed by an orchestra - the waltz, mazurka, quadrille, and march on the public holiday in Vienna in 1868..."
"It was 136 years ago! But modern artists of figure skating have to survive in the iron cage of the ISU rules, which make the space for artistic creativity in this cage smaller & smaller every year, forcing skaters to be more robots on ice instead of human being personalities."
"Let the skaters skate how they physically CAN in a free program. Let the coaches, choreographers, and skaters to think themselves, as an artist, how to skate, how to compose, and what elements would be more expressive for particularly music."
"Let them to create independently (without ISU standards) new fresh innovative movements, combinations, elements & they will do their best according to the personal abilities, because it will be the best motivation to work."
"Variety is the spice of the life. Variety is the spice of the figure skating."