Alternatively, we'll see a drop in deployment diversity, with more and more functionality shifted to centralised providers that have economies of scale and the resources to optimise.
E.g. IDEs could continue to demand lots of CPU/RAM, and cloud providers are able to deliver that cheaper than a mostly idle desktop.
If that happens, more and more of its functionality will come to rely on having low datacenter latencies, making use on desktops less viable.
Who will realistically be optimising build times for usecases that don't have sub-ms access to build caches, and when those build caches are available, what will stop the median program from having even larger dependency graphs.