P and NP
Technology may be wrecking the middle class.
This got me thinking about something my discrete math professor once said: "All problems in the world are either in P or NP. The problems in P will, inevitably, be automated and run by machines. Problems in NP are what humans are for. If you want to stay employed in the future, focus on NP."
For those not familiar with P=NP, Scott Aaronson sums it up nicely.
This is also a great writeup in the New Yorker.