I suspect the biggest effect will be that American companies will offshore more of their work (instead of bringing in the workers on H-1B visas) or open more non-US IT offices. Universities will open more programs in foreign countries to manage the loss in revenue and to help with the credentialing peoblem.

I would like to imagine this motivates them to invest in training native-born workers, but I really can't see that happening, given how they've operated the last 30-40 years.