I actually own the book "Catholic Prophecies" by Yves Dupont and I highly recommend it. But I have a hard time believing that the era of peace will be so short. I think Fr. Sylvester Berry is correct when he says it should last from 400-500 years.
No, it's easy to believe it will be short. People forget anything they haven't seen themselves.
People who were alive in during the (first) Great Depression are SO MUCH DIFFERENT from teenagers today. Look at how everything those people learned has already been lost. No matter how frugal, how holy, how down-to-earth, how hard-working they were, in only TWO GENERATIONS you have illiterate, lazy teenagers sitting in front of the TV/computer all day eating convenience food and scarcely knowing what work is.
Anything is possible after 50 years.
For another, more potent example, look at the Old Testament. No matter how fervently the Israelites came back to God, they always fell about 40 years later, because your parents can't learn a lesson FOR you.
Matthew