I will say this. If Nadal is forced to retire Nole will even surpass Federers 17 slams. A bit bold here but the possibility is VERY LIKELY unless Nole gets injured or something.
Depends on Nadals injury. If his knees can hold for a couple more years I really doubt it, he will end up winning a couple more but if his return doesn't work out and he has to retire then obviously yes.
If Nadal has to retire Nole might even surpass Federer. There is no real competition for the next years until Nole decides to quit so he can collect 2 a year easily imo if he plays 6 more years he can pass 17 slams. If Nadal is done clay is Nole's for the next 6 years no one can touch him there + Australian Open which is his too imo don't see anyone else who can compete so you have nearly 10-12 slams there and he'll win Wimby too at least 1 or 2 times more and USO too so really with Fed being done and Nadal injured this could happen.
No one can stop Nole at this point. The only one who can compete the best with him is a healthy Nadal.
Sorry mate, but how old are you?
You can't know the future in a such long term. Who knows? Novak could never win another major, he could lose a step in 2 or 3 years and all these players who came close to winning against him (ex Tsonga at RG, Wawrinka in this AO) will potentially beat him.
Federer longevity is an anomaly. It's extremely unlikely that Nole will win 12 others slams.
At Nole's age, Federer had 10 slams and Nadal 11. Murray will annoy him for many years, that's for sure. Tomic can very well improve his game and it's very likely that some youngsters will be able to beat Djokovic when he will be slower. At RG, he will be 26, he's not that young anymore.