Pay them more. Otherwise the work goes undone. Civilization is not entitled to cheap, disposable labor.
Or migrants get imported to do the work that goes undone, see EU.
“A crash” is just a Rube Goldberg wealth redistribution mechanism (wealthy people own the vast majority of securities and real estate). I argue a crash isn’t what’s needed: much more housing supply, robust antitrust enforcement (to keep monopoly pricing in check), efficient healthcare, living wages, and high progressive tax rates are what is needed to right the ship.
IMO it doesn't matter if you believe in fire or in ice, either will suffice. There's only one way forward.