The only reason I have confidence is because two years ago Magical Tux began transferring around 440k bitcoins in order to prove ownership of those coins:
http://www.reddit.com/r/Bitcoin/comments/n4a2o/someone_has_b...If he had 440k coins then, imagine how many he has now.
Yes, he could have lost a lot, but on the other hand we'd probably have heard if someone pulled off that kind of heist.
Here's how I expect things will happen: Gox will refund all "stuck" withdrawls. (Mine have already been refunded.) Then they will fix the technical problem, hopefully by Monday, but certainly within a couple weeks. Then they'll re-enable bitcoin withdraws. At that point, everybody will yank their bitcoin out of Gox. But then people will realize that there is value in trading on Gox as a platform, and Gox will be used for what it's meant to be used for: Trading, not storage.
EDIT: To clarify, I don't believe it's possible they had a technical problem that led to them losing more bitcoins than the profits they've made from trading fees. (This is me being hopeful that people can't be that incompetent.)