Theoretically, what would happen if every American job was outsourced?

[Deus Naturae]

If the President's job was outsourced, it would likely mean that the US was under foreign occupation.

Seriously though, the situation you describe is literally impossible. If everyone was employed by a corporation, all of which suddenly outsourced every single job, people could still be self-employed (if the corporation owned everything and they all suddenly pulled all of their capital out of the US, the country would likely revert to a primitive economy characterized by farmers, hunters, etc) or, if any capital remained in the US, they could start new businesses. And foreign companies would presumably want to sell their goods in the US, and would need outlets to do so, which they would need to employ people to run and manage. Obviously there would be incredible economic devastation, but new jobs would inevitably appear.

The exception to this would be if every person were incapacitated by, say, a self-maintaining computer, or a supernatural deity. Only a situation in which every person was literally prevented from moving could result in a 100% unemployment rate.