That's the question the article was trying to answer.

>>> "If you don't allow firms to hire immigrant workers, they just become smaller firms," Lewis said. "They are not replaced with US workers. Instead, the output of the firm shrinks, and there are fewer total workers."

So, no, if they had no choice they just shrink their operations, it seems. The apparent conclusion is that immigration bans will just force those companies to reduce operations or shut down, instead of paying higher wages to locals.