A big contributor to the housing bubble was housing developers borrowing a lot of money to buy land. After the bubble burst, they had to monetize the land in order to pay back the debt. Since all the big developers were in the same situation of needing to sell land, there wasn't anyone in a position to buy. That left them with only one way to monetize it: building more houses into a housing market that was already glutted. It was a vicious cycle.
Right now mining companies are in the same position. Most of the big miners, especially iron ore miners, have borrowed money to develop new mines. The market is on the verge of being oversupplied, but nearly all iron ore miners plan to increase production, and their significant debt levels make it tough for them to reduce production in a down market. If Chinese growth falls and demand falls significantly, the more indebted producers will go bankrupt. Even with a (relatively) soft landing, I expect them ultimately to go down 80%+.
That doesn't necessarily make them good shorts at this moment, however. Mining stocks have steadily marched lower during a bull market, and the bear case for these stocks and related securities like the Australian Dollar is well known among hedge funds. It's almost a consensus short, and I wouldn't be surprised to see some kind of relief rally. Just looking at the charts, many of these stocks like TCK and VALE look tightly wound and could easily bounce 20% in a few weeks.
An under-appreciated part of investing is recognizing one's psychological limitations and trying to minimize their fallout. I would be beside myself if I shorted these stocks, knowing that there was a high risk of a bounce, and quickly lost 20%. So I'm in the position of being very bearish but staying on the sidelines for now. If there's a bounce, I think that would be a good shorting opportunity.