If Djokovic comes into the season rested he'll have less than 10 losses again.
He's at an age where his movement should be there for a few more years.
Everything else will come from that movement, he'll be in position most of the time.
His endurance problems are of the past and that was one of his weaknesses.
With experience being at the top he should be even more relaxed in tight situations.
As long as his girlfriend doesn't derail him he'll be fine, as everyone knows, a woman can be a major problem.