I think if either one of them wins RG they will end up with the most. Kind of like the Fed Nadal AO. Had Rafa won then it's 15-17 and he had dominated him head to head. Then french coming up could have easily been 16-17. Now 14-18 seems unsurmountable at this point. Funny how one set changed tennis history. Had Rafa held his service games after that break up 3-1 in the 5th he would be right there in the GOAT talk with Fed. Now it's clearly fed. Rafa choked bad.
Rafa can get injured anytime. Djokovic on the other hand is top notch physically. So probably djokovic will get more majors than Rafa at the end of the day.
I doubt he wins 4-6 more. He turns 30 in 2 days. Slams are very hard to win after age 30. IF he bounces out of this funk he has been in(which it appears he has) I see him winning 2-3 more.