Sorry you couldn't access the article, I don't subscribe but was able to open it regardless. The article pretty much says that after nine years of a bull run and the US as well as the global economy hitting on all cylinders thing are almost perfect and when things are going so well it usually a time to expect the unexpected. They interviewed a number of financial personalities and their different takes on how things may or may not work out. Some saw the US tax reform as a vehicle with some yet to be discovered unintended consequences that may not bode well.
Nothing earth shattering but some food for thought.