Here's the tl;dr summary:
Even in a worst case, they found that new retirees who start with 30 percent in stocks and slowly increase that allocation by 1 percentage point a year to 60 or 70 percent in stocks would be able to withdraw 4 percent of their portfolio for about 30 years. Someone who held 60 percent in stocks and 40 percent in bonds over 30 years would run out of money two years earlier, but would also have to endure a bumpier ride, the researchers said. (These results assumes stocks will grow about 6.5 percent a year, on average and after inflation, while bonds will increase 2.4 percent).
Please don't discount it due to the last line, they ran trials under all sorts of assumptions. Pfau knows what he's doing.
In other words, the old advice was start with higher stocks, and ease more into bonds as you age (get more conservative as you age, the old rule of thumb was to have 100-your age as the stock percent of your portfolio). This article is saying slowly start buying more stocks and upping your stock exposure as you age.
My response is: ...yeah, and? We know stocks return more than bonds. If you can retire with enough money for a 30/70 stock/bond AA to support you at a 4% SWR, increasing the stock percentage will increase the longevity of your portfolio.
I think this is "news" to the mainstream, but - IMO - anyone who has studied ER, played with FIRECalc (now cfiresim), read the studies, etc.. It's not surprising.
IMO the best thing to do is just have a high stock percent (say, 80/20, or even 90/10) and learn some self control to not panic when the market is selling off. I understand some have a much lower risk tolerance, but if they do, and ER with 70% bonds, do you really think they'll have the courage to INCEASE their stock holdings in retirement? I don't. So again, best solution is to learn to ignore the market's fluctuations and ride it out (adjusting spending, if necessary, and rebalancing, but not selling off).
