Well, it is a lousy article. But I guess it is better than an article with only opinion but no data. He actually tries to bring data to illustrate his points. Unfortunately he used a very small subset of data just to back his points.
I am getting tired of people using last century’s US equity return to predict the next century. After all, from global equity market’s point of view, US was just a special case last century.
We are always in uncharted territory. Planning for your retirement 30 years from now is a crap shoot at best. It is important to hedge your bets.