While it's kind of obvious this is tongue-in-cheek, I feel obliged to consider it seriously for a moment. It's not even clear Secretary Clinton would be running, much less win the primary in four years and then go on to win the general election. In the post-WW2 era, the Republicans have had the longest period of control of the White House; the Democrats have trouble winning 2-3 terms back-to-back, much less 4.
So yeah, if I had the money I would bet against the Democrats winning both 2016 and 2020.