The latest price correction should have a chilling effect on difficulty increases. BTC price movements tend to occur quickly and are hard to anticipate, so load up on BTC while you still can... 
Except for the PHs and PHs of pre-orders which are going to be used no matter what.
If/when all the companies are selling from stock or have very short (say 30 day) pre-order windows the exchange rate might affect it but the "spike" likely drove in lots and lots of PH/s worth of pre-orders which will remain even when the price crashes back.
Bitcoin never going above $500 may have slowed pre-orders but the spike to $1200 and then falling back to $500 is just a lose lose for miners.
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