/usr/include/utmp.h implies that (part of) the limit is still 8.

I don't have full netbsd sources online at the moment, but from a long-ago 
grep through a source tree (for what somewhat later became System V Release 4) 
I found a fair number of programs that knew about utmp.  Changing, in other 
words, meant breaking a lot of binaries.

		--Steve Bellovin