Financial markets could be rocked, but the underlying (real) economy will be hurt much less, and will also benefit from lower oil prices in many ways.
But countries who's economy is based on Oil/Gas exports are getting crushed, therefore they can make dangerous decisions to change market forces. Putin turning of the NG spigot to Europe comes to mind. Keep you eye on Iran as well.
Keep an eye on capital expenditures.
If you see Caterpillar, Schlumberger, and other BIG capital expenditure companies hurting, that is where the rest of the economy will start to slow down.
I think, at BEST, we are headed for another recession. But I personally think it will be a lot worse. We just do not have the method of stimulating any more.