I think the next "Block Reward Halving", estimated for mid 2016, will have a significant impact on mining. If all mining operations just ignore it, their income will just get cut in half one day in Mid-2016. Since the larger operations usually have to liquidate some portion of their mined Bitcoins to pay for rent, electricity, salaries and the like, what's leftover will be reduced significantly. I would also venture to say that absent a corresponding increase in the price of Bitcoin, the value of the mining hardware will also drop in a big way, since each bit hardware doesn't produce as much per unit of time. Since I have zero idea what drives the price of Bitcoin, beyond the usual supply/demand theories, there isn't anything to pressure the price upwards. That ill crush many mining operations. I've said before, I can't think of any other industrial operation where this happens "overnight" like it will with Bitcoin.