It seems to me that if a company wants to get out of mining then the first thing they're going to do is to liquidate their hardware. And that hardware is going to get flipped right back on by somebody else. Supporting this view would be what happened after China banned mining. The hashrate collapsed about 50%, but then spiked back to higher than ever in a period of 3 or so months. So if we ever see a "real" decline in hash rate, it would probably take a very long form as hardware fails and isn't replaced/repaired.

As the hash rate gets more and more decentralized price tolerance approaches infinity. Some guy running a small number of ASICs at his house is going to have near zero price sensitivity.