I'm not sure. It seems like they are totally different metrics and visitors who came from another page on your site might be an interesting metric to cookie use

I'm not sure. It seems like they are totally different metrics and visitors who came from another page on your site might be an interesting metric to cookie users. What if you completely separated them, and tracked and displayed both for cookie users? Users who disable cookies would then have historical data in the same unit. Or a warning would probably work fine.