the exchanges need to separate their trading from their assets.

all assets should be held off-site, and updated every so often.  if the site is hacked or goes down, the assets are unaffected and can be gotten out.  yes - with the exception of the vanishingly small percentage that are actually involved with any issue.  there's no reason that trading can't be run against a real-time ledger, rather than against real assets.

80% of the Bitcoin economy was frozen for weeks by the MtGox issue.  there's no excuse for that.  people should have been able to get their assets out within minutes after it happened.  and trading would have resumed with barely a blip, somewhere else.