The only real problem with that is that with a small hash rate, bitcoin can be attacked more easily.
If bitcoin is the monetary backbone for many nations, they will subsidize miners to maintain the balance of power. That is the actual scenario that I'm optimistically predicting.
If bitcoin isn't the monetary backbone for many nations, by then, then it's probably a failure, and should probably be allowed to die.
It's also very possible that transactions fees alone actually will be sufficient to support a high enough amount of hash power to secure the network.