(Although I think the utility of server farms will not be high after the bubble bursts: even if cheap they will quickly become outdated. In that respect things are different from railway tracks)
The Internet bubble left physical artifacts behind, like thousands of miles of unlit fiber. However, that pales in comparison to the value of virtual artifacts like Apache et al. Similarly, the AI bubble's artifacts will primarily be virtual.
(Although I think the utility of server farms will not be high after the bubble bursts: even if cheap they will quickly become outdated. In that respect things are different from railway tracks)