Another way to look at it: if restrictions on high skill tech immigration tighten, then tech companies that would have been founded in America will instead be founded elsewhere.

This is more true of software than of any other industry, because software is built mostly with human capital which can cross borders fairly easily.

I agree with your conclusion (that tech companies will move), but don't agree with your reasoning.

It is exactly the opposite. Capital crosses borders much more easily than human capital. There are all kinds of impediments for human capital moving (visas, lack of money for travel, ties to families and friends). That is why, if it becomes even harder (because of travel restrictions), that tech companies will move.

Upon further reflection, I think it's not so much about human vs physical capital (and I agree with your point), but about IT workers vs other types of workers.

If a company of 5 Indian software engineers is booted out of the US, they can get together anywhere else in the world and still develop a product to the same standard. By contrast, other workers have "stickier" skills that tie you to a specific country. An Indian aerospace engineer may find it hard to find work in India, for example.