While your interest is in fintech, do take a look at the forces shaping the broader global macro economic environment because you can literally see some of these "open questions" playing out in real-time!

List of Unsolved Problems in Econ:

https://en.wikipedia.org/wiki/List_of_unsolved_problems_in_e...

What happens when central bankers run out of ammo and realize monetary policy may not be an ideal path to fiscal stimulus? Or having the bright idea of devaluing your currency to depreciate your outstanding liabilities results in a mutually assured destruction scenario when every sovereign on earth implements the same idea simultaneously? And when "too-big-to-fail" entities amass derivative exposure that is 100X global GDP does it become time to panic yet?

But still its innovations like ZeroCoin and SmartContracts that give one hope that out of the rubble, creative solutions will arise. As long as they are grounded in economic reality and not fantasy, humanity will abide...