The focus mostly last year was on Serena getting her calendar year grand slam but if you think about it, Novak, also, almost achieved that honor, if not for Stan winning the French.
I know the year has just started but with such good results last year, and with Novak winning one of the pre-Australian Open tournaments convincingly, he sends a clear signal to the rest that he, like, Serena, can gun for a career grand slam this year.
Of all the four grand slams, the Australian Open is where he has done really well, winning it 4 times in the last 5 years, and if indicators go, he could very well claim it again this year.
There are other competent players in his side of the draw that may hold him back, like Seppi, Pospisil and Nishikori. A semi-final meeting with Roger may be in the cards as well. Anyhow, those guys have to really raise their game on the day they meet Novak. He's just on a level all his own right now.