I'm a Rafa fan, but even I think that the OP is jumping to conclusions here. I honestly don't see how winning the AO will make him the indisputable GOAT.
...and *******s can lay off with the insults. If there is anything that we can pretty much all agree on, it's that:
a) Fed is at the moment the GOAT; but
b) Rafa is already up there somewhere, or at the very least well on his way
Fed has gotten to a point where even if he drops dead tomorrow, he'll still be topping the list. If Rafa drops dead tomorrow, he'll be nowhere near the top of that list. That said, he may well beat Fed if, and only if he follows our extrapolations. That means that there must not be a new player he will have difficulty beating (as Rafa is to Fed atm), and that his knees won't go kaputt on him (which has already happened once). Arguing that Rafa is better than Fed because of his winning record is a flawed argument; Kolya has a winning record against Rafa, but I don't see anyone arguing that he is better than Rafa, for example.
Where does that leave you? Nowhere; it's all speculation. At least *******s have got 16 GS, 17 Masters 1000, and 5 WTFs to cite; even with Nadal having more Masters 1000s titles under his belt, he's got to at least rival Fed's number of GS before you can even think about concluding Nadal as GOAT.
No reasonable human being is denying that Nadal is definitely one of the greatest players of all time; what I'm saying is that calling him the GOAT is just uncalled for. It's just too soon.