I'm not saying he can't do it, I'm just saying that people are being way too casual in saying that he will get to 12 slams. He has to double his slam tally right now at 25, will be 26 when RG comes around. I'd say he has about 1-2 years max to dominate like he did in 2011 and he hardly ever brings that level to court nowadays.
And the 5 slams in 2 years is a bit misleading in my opinion. 3 of those 5 were won in one year on the form of his life, and 3 of those 5 were won on one surface [AO]. Yes he can do it but realistically he won't do it I think, especially if Nadal wins more slams. I'd give Djokovic 10-11 slams max. Winning slams is not an easy feat.
Of course it's not an easy feat, but he's got already 6 and that makes him one of the best players in history, a legend. I'm happy with that even if he doesn't win any more, though I'm sure he will win a lot more. Nowadays these guys make it look easy to win a slam because there are basically 4 contenders winning them all the time. But it's a freaking stat.