Maybe they wouldn't! But OTOH the profit margin on an iPhone is still like 50% and people buy them all the time. Salaries keep going up.

I negotiated my salary with competing offers. If my company decides, after negotiating from a position of strength with their eyes open, that my salary is too high... that's a "them" problem. Doubly so if I had been employed for eight years and they've never complained.

The courts will treat it like a firing done for no reason at all (i.e. at-will employment). I personally shudder to think of staffing a company with the kinds of people who would put up with this nonsense, but the beauty of capitalism is that companies face financial consequences for driving off good employees.