VMS was a a reaction to UNIX, I'm not sure how different DEC's operating systems would have looked if UNIX did not exist.
VMS runs on ALPHA and ITANIUM systems, it doesn't run on anything that vaguely qualifies as a PC, unless you think Windows NT is a VMS variant. It's certainly influenced by VMS, but I say it's a different product.
At the very least, it was inspired by UNIX.
Where would we be? Probably all running VMS (which by the way runs on PC's). Or maybe WangVS or something owned by CA now.
//edited for typos