The only way for Federer to be a worthy GOAT candidate of any degree would be to:
-Win atleast 2 Calender Slams
-Wins slams over a 12 year span/13 year stretch so win atleast 1 slam in 2015
-Gain a winning head to head with his main rival Nadal in slams, so gain atleast 5 more wins vs Rafa in slams than Nadal can on him
-Beats Nadal in a French Open final atleast once
-End the year ranked #1 atleast 3 more times
-Gains a winning head to head with Murray, not even strictly the slams is good enough in this case but overall
If he achieves this it would put him in the conversation with Laver, Sampras, Rosewall, Gonzales, and Borg. Right now he is in the second tier with people like Tilden, Budge, Kramer, and Perry; just above the 3rd tier of Lendl, Connors, McEnroe, Cochet, LaCoste.
Sorry kittens.. but you are placing Sampras above Roger?? when Sampras never cared for clay, doesn't have a title at RG?? I think you are misleading some here... Let's put it this way.. Sampras never had a rivalry vs. a clay courter.. why?? Cause he never won a major title on clay, hence, he never had a rivalry with pure clay courters in his time... he only got to the round of 16th or even his ONLY SF at Roland Garros.. Fed has made 4 finals at RG because he is the 2nd. best clay courter in HIS era.. Sampras wouldn't even be considered top 10 material on clay... and you are placing him above Fed?? That's a double standard argument... IF Sampras would have gone to 4 finals (and consecutive finals at that) and lost each one of them to probably the best clay courter of all times, then you wouldn't be saying these things!!! Truth is Sampras never cared for clay, hence not even 1 final at RG... I mean, come one.. you are a tennis historian

you of all people should know that Fed vs. Rafa H2H goes specifically on the side of Rafa cause they have played mostly on clay... if you took out clay out of the equation, you would have a 5-4 lead for Roger... so, by your standards, this H2H would be the one to take into consideration IF you place Pete as a possible GOAT.. why?? Cause Sampras was NEVER a threat on clay, never managed to reach a final at RG, have just 1 SF at RG, lost to NOBODIES at RG, except for that SF... Put it this way, you say Agassi is probably one of the most overrated players... BUT if Sampras would have played vs. Agassi on clay several times, the H2H between those 2 would be even closer or even tied, cause Sampras never had a shot on clay vs. mostly anybody.. and we would be talking that the only reason Agassi was closer to Pete in their H2H would be because they played a lot of matches on clay...
I don't believe I am going to say this, but you are coming out a little biased in my opinion...
You give your reasons for being a GOAT, but you are not respecting his achievements either...
He just tied Pete Sampras for 14 majors... FED has a Career Grand Slam (Pete doesn't), FED has 20 SF in a row, who has that???, He has been in 4 finals at RG, how many did Pete achieved?, He has won 5 wimby's in a row, 5 USOs in a row, consecutive number of weeks at #1, a lot of more feats... and you are just dismissing this... why?? your old "weak" era argument? I mean, come on...