I agree with you in the broad strokes, but replacement by LLMs isn't the only way the level of employment can be reduced. If LLMs can make it so that two programmers can do the work that used to require five, that can result in a very large reduction in employment, even while having (some) programmers is still essential.
On the bet that layoffs will result in programmers ending up at 40% of the staffing level they are now, I will take the over.
Only if there is no further additional demand created by the now lower cost of doing the work. Take lighting as an example. As it has progressed from burning expensive candles to now leds, our demand for lighting has continued to increase.