I agree with Andu here. Where I fly in Oz, there are hardly any oneway routes outside radar/ID coverage and I marvel at how little lateral sep exists when I pass jets going the opposite direction every day. And I certainly concur with the comment that when tracking with VORs/Omega, there was always an "inbuilt" track error that helped the big-sky theory work.
We are already officially allowed to offset to the right in Australian OCA, so why not by a little bit in continental airspace?
There are problems that will need to be overcome though:
+ some FMSs cannot be set to terminate an offset at a downtrack waypoint, so the crew has to remember to do that later on,
+ some FMSs cannot have an offset of less than 1nm,
+ many NPAs are flown in LNAV, and there would have to be some FMS reprogramming to prevent a crew inadvertently leaving an offset in during a approach.