I think you are being too narrow in your focus. I have been seeing developers/builders in Florida, and farmers everywhere, discussing how their business model is screwed by the loss of illegals. And the hospitality industry will be hard it as well. In a time of corporate gouging/inflation and business/govts refusing to raise wages this is only making things worse for average Americans.
At first, I thought you were merely a gadfly in the ointment. It can be interesting and you can offer alternative insights.
However, you have to be careful to not to throw out too many ideas that don't hold well together. Sure on social media, you will find people on both the left and the right who will simply nod along.
Yeah, that's right.
Change is always going to be bad for someone. I was reading your first point that illegal immigration is part of the business model. I don't see why anything illegal has to be permanently and unofficially in code. Yeah, I know contractors who do very well that know how to tap into a steady stream of illegal migrant workers. There is an informal network in place.
If you think about economics objectively, no industry will be completely screwed. You can predict wages in sectors will go up. Industries under strain (i.e. agriculture) will lobby for temporary work visas. Will profit margins be reduced? Of course. In the short run, most certainly. If you built a business with illegal migrant labor, you were likely able to make some decent money.
When the economy changes as it always does, it's impossible to predict where supply, demand and profits will be in the future. Here's a point. The hospitality industry will adapt. Countries where the minimum wage is comparably high with tight migration have restaurants that don't offer table service in even mid-level establishments. It's obvious that many uber and taxi drivers are immigrants. Fares will go up. Technology might make drivers a moot point. The economy is always changing, innovating and adapting.
In the U.S. we are accustomed to a high level of service because as you pointed out so eloquently we have always had low wage, black market labor. Most Americans don't think that needs to be or should be informally codified. Then you can break your argument down with numbers. What is the correct number of immigrants? Did the U.S. need ten million more people come through the Southern border over the last four years. Before that, empirically wages for low-skilled were going up before that (I think that's good, yes?). There didn't seem to be any major sticking points in the labor market. I think it's healthier for the economy to have some competition for labor at all levels.
Lastly, you're forgetting that the workers in ag, hospitality, drivers etc. are not planning to stay put. They're going to try to move into better paying jobs competing with the very people many here claim to support.
To paraphrase a famous singer-songwriter, all we are saying is give restricting the supply of labor a chance.