A writeup on Xenix indicated it had huge impact in getting UNIX into more universities and created tons of market demand for PC UNIX. If that's true, then it's not so much an insignificant blip as a huge part of the reason for FOSS UNIX's success if they benefited from contributors from those universities or demand they generated.
Then it becomes a relic of history with lasting influence from there. Unless you count the Linux distro's people paid for. Two of those are still leading with a more, usable one mostly happening due to paid, support model. Seems like proprietary UNIX on PC's just shed its skin and took a new form that dominates UNIX on PC's to this day albeit with more benefit to users. ;)
http://www.softpanorama.org/People/Torvalds/Finland_period/x...
Then it becomes a relic of history with lasting influence from there. Unless you count the Linux distro's people paid for. Two of those are still leading with a more, usable one mostly happening due to paid, support model. Seems like proprietary UNIX on PC's just shed its skin and took a new form that dominates UNIX on PC's to this day albeit with more benefit to users. ;)