I think it will. For years, most of the illegal border crossers from Mexico were Mexicans or South Americans looking for work. There still are a huge number of them. We can stop those by making it impossible for them to get jobs here - and that won't happen unless the employers have a legal source of workers.
At that point, most illegal crossers would be drug smugglers, terrorists, those fleeing justice in their own countries, etc. That's a much more manageable number.
I think it will. For years, most of the illegal border crossers from Mexico were Mexicans or South Americans looking for work. There still are a huge number of them. We can stop those by making it impossible for them to get jobs here - and that won't happen unless the employers have a legal source of workers.
What it sounds like you're saying is that the illegal workers currently in the country, if legalized, will take up the jobs that foreigners from the south would be coming here for, and thus discourage them from coming. But if that's the case, then the illegals currently in the country would already be taking up those jobs. Making them legal won't change the economics of that situation.