It will be interesting to see the impact on oil producing nations, if the price of oil plummets most of them are going to be in real trouble as few of them have diverse economies.
It has already been happening to Russia the last few decades - as the price of oil rose then fell it played havoc with their economy and government budgets
We already are seeing what happens to the likes of surprised countries like Columbia and Zimbabwe and worried countries like the Kingdom of Saudi Arabia. It's a big deal and diversification is not an option, it's the way they need to go.
Given how much they depend on that wealth, and how unstable that part of the world is...