If there's a significant dip in stock market, then there's a possibility we'll see HUGE amounts of corporations going under and massive lay offs. This will most likely end up causing other markets to fall depending on how much they've bubbled due to QE. Housing crash is hard to say; there can be another "too big to fail" pay off because a lot of these banks hold federal debt (might as well pay them once instead of twice), or the government might just say fuck 'em which will cause our whole fiat money system big problems (because we'll likely losing trillions of dollars in a blink of an eye). Basically a housing crash not subsidized by the government = whole economy collapse. Bonds market crash will mean that government has to increase rates significantly to entice buyers so debt doesn't get out of hand (this can lead to a stock market collapse as well) or if they don't increase rates, then it will devalue our fiat money system.

I believe we haven't recovered because a lot of corporations converted a lot of their full time positions to part-time, so there are not a lot of quality jobs anymore. Since there aren't a large majority of people making "real" money anymore, they don't have money to spend. No money to spend = no money to earn. No money to earn = no money to spend on employees. This goes on ad-infintum. The market will correct itself, but it takes a LONG time; especially after a huge recession like 2008. Our economy is so intertwined, that bad corporate sales while QE is happening basically bubbles investment markets. You can't QE forever because federal debt is high and they need the interest to wipe the slate clean, but if you don't QE, then corporations will fail.

Long store short, we're hanging on by a thread and the next recession is going to be BIG. We just don't know how big.