i think we should worry more about the fact that mark karpeles still holds like 400-500k btc. the bitfinex hackers can't dump all their coins at once without getting noticed. they have to mix and sell their coins in batches of 5-10btc per time. with such a pace the market won't feel it.
I'd say that the market would rather feel the
lack of 120,000 bitcoins that got stolen at Bitfinex. In this way, if an exchange is hacked every month (okay, every other month), the price of remaining bitcoins would certainly hit the sky (and then the moon)...
And Bitcoin would become as rare as hens' teeth