Now it makes no sense at all.
FreeBSD made the explicit decision when disks were sneaking up on 2TB to move to GPT labels. Why invent a new scheme that interoperates poorly with other things? GPT, for better or worse, won. disklabel64 would add no value over GPT, require a lot of extra code and be an ongoing source of confusion and difficulty for our users. This is why UFS2 didn't bring in a 64-bit disklabel format...
NetBSD is, of course, free to do what it likes. My semi-outsider's view suggests, though, that the FreeBSD experience is relevant and timely.
Warner