I am always actively recruiting mid to senior level candidates out of FANGs. I would say about half of these people are seriously poachable, given the right opportunity. For the other half, their compensation is simply too high to pull them out. If FANG salaries dropped by half, I estimate the number would increase to 80-90%. If venture capital funding dried up such that FANG salaries decreased AND Series A+ startup opportunities dried up, then I'd predict a reversion to founder-heavy garage based startups. Because the one thing that is not going away in the near term is the sheer number of unsolved problems/opportunities in tech.