and it's extremely difficult to find qualified people to fill those positions
My department is having the same issue with hiring people. We can't find people with the technical experience we want... at the rates we're willing to pay. We're getting tons of responses from India though.
Pretend we doubled the salary on our open positions... we would have gobs of Americans applying.
Let's do the opposite thought experiment to understand how this works. It's just supply and demand. Pretend 50% of the workforce is H1B and 50% citizens. If the H1B was stopped overnight, 50% of the workforce is gone and the remaining 50% of the workforce just got a lot more valuable. Higher salaries. This is what helps balance things. Higher salaries means it looks like a more attractive field. People in the field would be treated better (because they are more valuable). All of this leads to more people entering the field. Salaries raise and people are treated better until the field is at a better balancing point with the demand. It might even turn into a respected industry!