[Dagonfly]

"Widespread" was maybe the wrong word, I was mostly imagining virtual memory on servers.

Currently, not all 64 bits are available for user-space VAs. Even with Intel's 5-level paging you can "only" get 56-bit (128 PB) of virtual addresses. On ARM they reserved parts the top-level byte for memory-tagging as well.

Remember with pointer tagging and overcommit you might have orders of magnitudes more VA address space used than available RAM. Exhausting 128 PB of virtual addresses in the next 40 years does not seem unfeasible to me. CHERI already exists in some niche.