Seems to me that Schaeffer's 7000 could replace any synthetic oil for a 8000 mile oil change and even flow pretty good in the wintertime. And without any of the drawbacks of the synthetics: poor UOAs, too thin, no API certification, etc.
Chevron Supreme or Pennzoil would be good enough for anybody doing 3000-5000 mile oil changes.
Only time that a PAO or ester synthetic would be required would be for extreme cold (or extreme heat), maybe towing, and for vehicles that require synthetic oil, such as the Corvette.
Otherwise, two or three motor oils would fulfill the needs for 90% of everybody.