Although it could have some impact, your money isn't "locked" with MtGox due to being able to transfer it to another exchange as Bitcoins, and cash it out as another currency there.
Most on Mt. Gox don't have secondary accounts, and this is more likely for those who are looking to make short term $ (and who tend to panic sell). For the various exchanges they could move to, what's the turnover time to be able to trade and more importantly, make USD withdrawals? Will the other exchanges be ready for this? How exacerbated could this be if there's a price drop?
A comment based entirely on speculation. Do you know for a fact that most people on Mt Gox don't already have another account elsewhere or can't figure out how to create one?
Little affect these days. There are other brokers out there which helps stabilise the price of bitcoin.
Price has been pretty stable for awhile now. There's always 'the crazy periods' when it get's hyped up and the price is all over the place, but in general the price hovers around plateaus. Currently around ~$100.
Possibly raise the price on MtGox as people who want their cash will have to buy BTC with it and then sell them for USD elsewhere.
Buy it from whom? Who is going to sell BTC for USD without some confidence that they can actually receive the USD from MtGox?
Any news, no matter what it is, immediately causes panic selling. So, short term price drop. Then? Who knows?
Except that it's up slightly since this news was released.
Well, yeah, since its negative news for the expected future value of USD balances currently held on Mt.Gox, the natural result is, at least in the short-term, a drop in the value of USD on the Mt.Gox exchange, which, ceteris paribus, implies a rise in the BTC:USD exchange rate on that exchange.