Barring injury, he's got 2-3 years at best of being a serious contender. But Nadal doesn't even need to pass Federer necessarily. All he has to do is get close. 14-15 slams, with his head to head record over Federer, would give him the edge all-time in a lot of people's minds. But in order to do that he has to stop losing to Djokovic in slam finals, he's got to get back the number one ranking, and he's got to win a few more on other surfaces. I don't know that he's going to do that. It's possible if no other great player emerges for a few years, and Novak slows down a bit. But if he loses tomorrow, it'll be a huge blow. Remember, he was up a break in the fifth in the Australian final. If he'd pulled that out, and then this one, he'd be at 12, and Novak would be at 4. Now it could be 10-6, with Djoker doing something Roger never did (beat him at Roland Garros.)
Before he can worry about all-time records, he has to worry about the guy breathing down his neck. Novak probably has four more good years in him, and I think will be in better position to steal an extra slam or two around the age of 30 than Rafa, whose game has been so punishing on his body. Plus, there are two hard court slams a year, as opposed to one on clay, so that is double the opportunity on Novak's best surface, which also happens to be Rafa's weakest. Djokovic could easily end up with more than a dozen slam titles of his own.
Take care of business tomorrow, and Nadal will have to feel like he's got his mojo back a little bit. He can go into Wimbledon thinking if he gets this one, he's back on top. Lose tomorrow, in the slam that he has owned, and he's got to be feeling like he literally has no answer for Novak.