Our economy absolutely would collapse. Our entire farming industry exists because of heavily abused immigrant labor, and is a job that Americans refuse to take. We've made multiple swings and attempts at getting Americans to do this work [1] but it's low pay, low benefits and grueling work. Farmers literally could not afford the actual salary needed to attract people to do said labor, and it would cause food prices across the US to skyrocket.
The only way this would stabilize is if the government came in and subsidized and socialized farm work heavily and that would also never happen.
Of all illegals disappeared Thanos-style, the end result would be massively expensive certain crops, and a greater dependency on machine-farmable crops, like corn.
And some weird severe-but-short-term economic volatility.
Something along the lines of:
Now nobody is picking fruits, all the fruits die on the tree/vine, so there's none of that in the supermarket and those farms go bankrupt. Also, most of those who were paid to butcher the cattle are gone, but the cows are still there, costing the farmers money, so those farms go bankrupt. And then so do the feed suppliers for cattle farmers that don't ranch (or do but need extra feed besides the grass). But everyone still needs to eat, which means there's correspondingly more demand for the stuff which is heavily mechanised, so prices for that go way up, but because this is an instant supply shock the average person is still hungry no matter what the prices are, unless the humans start eating alfalfa en-masse.
Not only that, most of the construction and home services companies are usually the white American folks that come and give you a very inflated price and then send you the immigrants to do the actual hard work. It's crazy when you speak to the people doing the work how much they are getting paid vs how much you are paying.
The only way this would stabilize is if the government came in and subsidized and socialized farm work heavily and that would also never happen.
[1] https://www.npr.org/sections/thesalt/2018/07/31/634442195/wh...