It’s not going to be oil prices this time, particularly given the US fracking boom. The article gets into what other factors could be. I’d say there’s going to be a correction in the stock market (they’re all overpriced at the moment, the prevailing theory is that the market is expecting tax cuts, which depends on political ability to get things done), then consumers will cut back. Or there will be a massive crisis of confidence in the American economy due to political instability (someone gets impeached, healthcare bombs, Russian influence proves more invasive than originally thought, we bomb someone, who knows?), no one wants to invest or expand their business, everything spirals.