Nouriel Roubini is known for his bearish prognostications. And unfortunately, he still doesn't see any good news on the horizon. In fact, things are going to get much worse, says the famous economist and author of the new book "MegaThreats: Ten Dangerous Trends That Imperil Our Future, And How to Survive Them." He believes that due to a rolling series of supply shocks, some of which are still unfolding, we'll have a severe downturn before we get relief from inflation. Unlike the 1970s he says, high levels of private sector debt will make it harder to fight higher prices, and that central banks will reverse course as things start to break in financial markets.