I think this is a rather pessimistic view of the benefits of hiring intelligent and hard working people to work for your country's companies. Its most certainly not in the disparity of pay; more because they provide more value, due to said intelligence and proclivity to work hard.
I don't see it as a pessimistic view. Any employer committed to rewarding people for their value shouldn't need to rely on an omnipresent threat of deportation. I see myself as optimistic that such employers do exist, and should be happy to both recruit such foreign workers to US shores, and happy to poach them from other US firms.
Free movement between employers would likely free up only places like Wipro, Tata and the like, whose business models appear to rely on disparity of pay.
