Entitlements killing the middle class?

Mark Perry brings us the possibility with this graph.  The median income drops as more people leave the work force, with a 90 percent probability.  Obamacare adds to the problem with middle class tax hikes.

How did many Kanosian economists miss this. They are not well grounded in  random processes and spectral theory.  If they had the knowledge, they would have known that the entitlements drift out of balance unless they ate updated every 15 years or so.  This is self adapted statistics.