Irish oddsmaker gives 33% chance Trump will be impeached

[Labster]

By ending immigration, you stop them from having a pool of unskilled/barely skilled people that will work for lower wages to pull from. To keep the necessary number of workers (because let's face it, if it could be automated, the farmers and the packing plants already would have) they will raise wages. Nannies and housekeepers will either be done without, or else be jobs taken up by teens/college students and those with little to no ambition in life, the second, freeing up a number of fast food jobs for teens in the process.

Actually you raise an interesting point parenthetically, but mangle it mostly.  Companies pay wages when they are cheaper than automation.  A lot of manufacturing has returned to the United States in the past 10 years, but jobs have not returned with the industry.  The reason is that it's cheaper to be automated than to pay people in the U.S.  Outside the U.S. humans are used, because the wages are cheaper.  Given enough capital, industry will choose the lower price point.

The main exception to all this are the few industries that have already hit the wall on automation, largely car manufacturing.  Elon's recent experiments prove the point that the industry is already maxed out on robots, and attempts to add more will not work with current tech levels.  Agriculture, in contrast, still has places to automate, with watering systems, harvesting devices, and planters.  People are now at work on robotic strawberry pickers, so if it hasn't been invented yet, maybe it will be soon enough.

Your example of "fast food jobs for teens" is laughable, first for the assumption that fast food jobs should or are currently filled by teens.  But the deeper problem is that automation is just getting started in the fast food industry, because of the abundance of cheap labor.  Over in Europe, where it's more expensive, McDonalds has touchscreens that let you place your order, even customize the product.  Imagine taking orders and paying with apps!  If the labor market tightens, less people will be employed in fast food than currently.  This even extends out the the casual dining market segment -- Outback Steakhouse has little credit card readers at every booth, so servers don't have to take money.  Self-checkout at grocery stores is just the start, as Amazon already has a few cashless stores where customers walk around with barcode readers.

In short, software is eating the world, and humans are already competing with robots in the workplace.  Limiting labor supply drives the price point of human services in many industries to the point where automation is the long-term cheaper approach.