The annual operating cost of these is <10% purchase price annually. Even if the B200 is 10x more efficient in practice you can still operate the H100 at profit.

As it stands there's way more demand than supply. The new GPUs are going to run frontier models while the older ones serve smaller ones.

That said some of these are running in tents hooked up to mobile turbines. I can see some of those going away but generally I think you'll see them used until they start to fail in 5-10 years.