alt Hacker NewsYes NeXT/Apple survive, although they commodity m68k CPUs, not quite your traditional UNIX minicomputer. Those were IBM, Sun, HP, DEC, maybe SGI. Designed their own ISAs, CPUs, interconnect fabric, 3 of them did their own silicon manufacturing.
One does still survive though, that's IBM's POWER / AIX. Still actively developed, though there is the feeling of 'when' rather than 'if' for them too.
I did not count AIX / Solaris in, because they are always some racks in a server room, or the whole IBM / Unisys / Fujitsu for that matter.
I was only thinking about UNIX workstations, those under/besides the desk.
Otherwise you're right, there are few more options available still.