You can take decades old fibre, stick some new transceivers on the ends, and have it run at the very latest speeds (unless it's cheap, damaged, etc) without having to pull it out and reinstall it.

H100s will not age this well. It's not like owning old railroad tracks, it's like owning a fleet of 1992 Ford Taurus's. They'll be quickly obsolete and uneconomical in just a few years as semiconductor manufacturing continues to improve.

For me that brings up two questions:

1) Will I (and others) be able to get a H100 (or similar) when the bubble pops, and would that lead to new innovations from the GPU poor?

2) Will China take the lead in AI as they are less "capitalistic" with the demands for outsized returns on their investment compared to US companies, and they may be more willing to continue to sink money into AI despite possible market returns?

I doubt it.

Some will be used a lot will be written off and tossed away.