Yes, in the United States, even if you don't come back, you have to file income taxes on that foreign income. There is no differentiation between foreign and domestic income (although you can get tax credits for foreign taxes paid).
That's true if the "you" we are talking about is an individual. If the "you" is a corporation, they are taxed by the US when they bring that money back to the US, not when they earn it abroad. They can defer the tax arbitrarily by not bringing back the money.
