And then what? There will be no demand for engineers in the United States? I suppose that is possible; but it is also possible that we will be hit by a giant asteroid.
My guess is that the practice of engineering will change in ways we cannot imagine, but good engineers will continue to be in demand for the next few centuries at least. Unless that asteroid wipes us out first.
its going to become a niche profession in the US, and a profession for engineering managers. that's what's going to be left - the top schools like MIT producing cutting edge graduates, and others in the field had best include an MBA as part of their science degrees, if they want jobs where they don't have to compete with workers in India and China.