Or 'undisputed' train has already sailed?
Even if Federer maintains the four Slam lead which today appears nearly impossible, he STILL will have trouble assuming the undisputed mantle unlike Ali, Jordan, Nicklaus etc. And besides that (Slam lead) there's NOTHING (WTF, Masters, Career Slams, Weeks @ No. 1 etc.) Federer can do now - realistically - to move the needle.
If that's a given, Federer is then just waiting to see how battered can his 'disputed' status get - given where Nadal ends his career with? And that's assuming he is not demoted to GOAT (b) condition - if not totally eliminated from the GOAT discussion.
Nadal, OTOH, has that WTF hole that may deprive him of undisputed stature EVEN if he matches Federer's Slam total. Heck, even passing may not do it - unless of course it's 'laden' with a Slam lead of what two AND maybe a third (two more AO titles and one more Wimbledon) Career Slam (negating his clay only criticism)?
That's tough but with Nadal you can never be sure. However, IF he does all of above, other periphery factors (H2H, Olympic medals, Davis Cup, Masters, Year-end No. 1??) may close in to allow Nadal AT LEAST the MOST 'on the outer perimeter' of disputed status, if not outright undisputed one.
As things stand today, Federer clearly has the 'advantage' BUT Nadal has the FAR higher probability of getting closer to 'the most distant disputed' stature, if not an undisputed one.
What's more likely to happen?
GOAT (a) and GOAT (b) determination?