Earlier quoted context omitted.
Lots of people in this thread seem to think that there is either no incentive for Coinbase to conduct their business legitimately, or that the law is the only incentive. That ignores the much more obvious and presumably stronger incentive: they should be able to make a lot more money as a legitimate business than if they just ran away with one lump sum.
That relies on the assumption that they will not suffer a tremendous loss due to a rogue employee, a software bug or a malicious hack. If they found themselves in a situation in which they are certain to go out of business as soon as people find out that they are in trouble, that motivation would cease to exist. It would come down to ethics, reputation, pressure from investors, etc.
This is in no way rigorous but consider User Interface design as a rule of thumb. Gox had an ugly unintuitive site. Coinbase on the other hand has a polished UI. This attention to detail suggests that the people who operate Coinbase are very different from those who operated Gox.