You are commenting pretty well in your post, but you're talking about the future, and one that is over a decade out. If you zero all foreign workers today, an economy our size will not tolerate it. By the time your decade arrives, there will be another Great Depression in the history books, only in this one it was our parents who died at 60 of no heat in winter -- not our great grandparents.
How do you "zero all foreign workers?" We have one million LEGAL immigrants coming in every year plus an H1B visa program currently capped at 65,000 per year. We also have other visa programs for investors. If we need more workers, we use legal ways to get the kinds of workers we need to operate the economy. Simple as that.