This is an interesting thing to trend, especially since it has been just over a year since @sama put out his famous bet (
http://blog.samaltman.com/bubble-talk).
I think the author may be conflating (as most do) VC investments at the left side of the power-law curve, and those on the right side. Meaning that the investments on the left (that produce at least 100x returns) are likely valued correctly, whereas investments on the right (at the tail end of the power law curve -- or even those in the center) are supposedly overvalued.
Even so, the Inc author's insinuations about Uber and Airbnb are not exactly the smartest things I've ever seen written. Since I fully expect that within 10 years Uber will be running a massive network of electric, self-driving cars and busses (and perhaps even long-haul networks?) in every major and even minor city in the world. The global transportation infrastructure is absolutely worth MUCH more than $50bn.