Since trading began in 2010, the trend for BTC volatility appears to be downward:
http://www.coinometrics.com/bitcoin/bvix.
This is strong evidence that as adoption increases, bitcoin will become less volatile.
Yep, surprising that most people (well, journalists anyway) ignore that obvious fact; I guess that is because they look at absolute numbers, "oh look bitcoin crashed $300" while it's actually a 20% move. Another metric which is somewhat related is how much value, in percents, is lost from local maximum to the following local minimum, it progressed like this: 93% (end of 2011) -> 80% (apr 2013) -> 64% (dec 2013, assuming it is over) so extrapolating (I know, I know, but three points is already something) -> 50% somewhere in 2014, and stability should arrive in 2017, which I also think would be around the year of worldwide adoption (unless it crashes to zero, then not).
Yet another reason that we need mBTC as a default. Nobody would bat an eye at a 30 cent crash.