If Federer retires at 17 Slams and Nadal is unable to break the record, do you believe somebody else at some point will break it? If you think about it this way, Sampras set the 14 Slam record only in 2002. It ONLY took 7 years for somebody else to come along and break it! If somebody else emerges in the next few years and the competition is weak, he could go onto a tear and rack up a lot of Slams. Nadal looked like he was closing in on it until Djokovic came to his prime. So likely somebody else in the coming years will set a new Slam record. Basically Nadal is the best candidate to do it but I don't see it happening now. It will have to be somebody else down the road.