I love that he says Novak could even be the best on clay in 4/5 years. Seriously Srdjan. Novak will NEVER reach Roger's achievements - get over it. And in 5 years Novak isn't going to be doing much on clay.
He's a great player and he acknowledges other great players - his parents however talk about "the child of God", destiny, the "best ever" etc. Neither the Nadals or the Federers have this kind of attitude - class there. Poor Novak.
Dunno what sports you're watching but Novak will still be playing at a high level 4-5 years from now when Roger is retired and Rafa will have fallen off considerably. At this point he will be competing with guys like Raonic, Tomic, etc. so no, it's not crazy to think he could rack up many more slams if he stays healthy and hungry.