The thing about Djokovic compared to Federer is - there are far fewer parts to his game and therefore fewer things that can go wrong in his return. If he's healthy, fit and mentally ready - he''ll be money by the time the AO rolls around. He's supposed to play 2 warm up events beforehand - an XO and Doha. So he should have worked out some of the kinks by the AO. I doubt either Federer or Nadal will want him in their half - especially in the early rounds. Djokovic's first tourney is Doha and even after 6 months off he should be able to defend that title (other players in the draw - Thiem, Berdych, Tsonga, Gasquet, Carreno Busta, Verdasco) and build confidence and momentum heading into Melbourne. If he defends he goes into the AO ranked #11 or 12. If he doesn't make the final he could be ranked anywhere from 16-20. I'd put money on him hitting the ground running and not wanting to be seeded any lower than 12. and hope for a decent draw.
Re: Young guns making a breakthrough? I think Federer said it best after he won Wimbledon - the changing of the guard is still at least "a few years away." The young guys will move up the rankings...but I don't think any of them will win a Slam in 2018 unless they get lucky like Dimitrov and the draw is decimated by injuries and early losses by the big 4-5.
I don't think any of the big 4 will play a full schedule and go through the year unhampered by injury.
Murray is a confidence player, he's like a coil that needs to incrementally get better - he's not a player I see coming out of nowhere (I mean poor form and injury) and surprising anybody. When he's been at his best in majors, it's on the back of good results and good form. There are question marks over his fitness already. I don't think you'll see anything approaching his best form until Wimbledon... if you're lucky.
Nadal by all accounts is still not fit...
Djokovic has huge question marks - nobody has seen him at his best for over a year and a half.
Federer is an old man, will either skip the clay season altogether or play a very limited clay swing... and there will be question marks over what he can realistically schedule into the year...
Put it this way... you'll likely never see these four players at their best, at the same time (for an extended period)... ever again. The status quo has sailed.
