Hmmm. I'm sure there will be an impact, but don't think it would be that significiant. A global talent pool of top engineers who can join the competition is already quite limited, and a fair share of them is already in the US, whether born there, on visa, or have immigrated. It shouldn't be ignored that major companies like Google, Microsoft, Airbnb, or even Duolingo has already been operating in multiple global offices for years, that includes all those consulting agencies who's done that for god knows how long.
Some founders, and engineers, have those sort of fantasy that they can hire with way lower wages or something like 1/3 of the cost for equally qualified engineers. Wrong, immigration isn't that hard, even easier for Canada, it will take time, but people might be willing to gave up 25% or even 30% of their salary to live in a place that's of lower cost, where their family reside, but they are not going to gave up 2/3 of their salary, when they could have immigrated fairly easily. The cheapest and easiest way is probably to attend a shitty school and graduate, the only cost is time.
The only impact I see is it's now way easier for smaller companies to hire and operate a team globally, even for 3-5 people, previously it was reserved for major corps and giant consultancies.
People sometimes tend to ignore that people create value for the company, not the other way around.
Also just as a side note, many countries in this world have company-paid salary tax (somewhat similar to FICA, but are paid at a much higher percentage in some places). This often gets ignored in salary comparison.