CAMELOT FANTASIES

All true general, and yet, it is probably his reaction to his own dissatisfaction and others criticism about his play, and the challenge of facing new generations of players, and breaking more records that keeps him the most motivated to still compete at a high level. 

He's amassed all of those things you mentioned, has the respect of people world wide (#1, since Nelson Mandela died) and almost anyone would be satisfied with all of that.  But it's also a big responsibility.  He still attracts the biggest crowds, even if his results suffer.  He knows when he doesn't play, tournaments suffer attendance and ratings drops. 

If he were completely satisfied with his career,  he might have called it day by now.  Then again, for the most part he still loves to play tennis and has a way of putting poorer play behind him.  It's the rare people in the sport that can motivate themselves to win repeatedly and still want more.  Some might portray as greed.  I prefer to think of it as the unquenchable thirst to achieve.  It's obviously not the money or fame anymore.   Rafa is in a similar situation, Novak to a slightly lesser extent.

Roger could have gone out on top in 2012, at age 31, after winning a record tying 7th Wimbledon and returning to #1 in the world, winning another Olympics medal, all against his toughest rivals and competition of this age, over 8 years from when he first achieved #1 ranking in early 2004, and at least a generation of players later.   But he didn't.  Why not?  As you said, he has it all.  To me, it can only be for the love of the game. 

After the rigors of 2011-2012, where he won 9 tournaments in 9 months, he knew that 2013 would be an "off" year, or as he said before the year started, "a transition year".  He knew he would be experimenting with racquet changes, face defeats and criticism, yet he pressed on even through his recurring back problems.  In 2014, he seems to be playing with renewed vigor, excited at the thought of his country's Davis Cup team having an excellent chance this year, and very happy for his compatriot's slam win in Australia.  Perhaps he is still hopeful of having a chance to win an all time record 8th Wimbledon title, or maybe a 6th US Open, or maybe in the long term a 100 titles.  There is no doubt he is also looking at the record books for motivation.

Roger Federer could probably play into his 40's for the love of the game if he doesn't suffer too much from his back problems or other injuries and too much decline in play.  He could probably play doubles until 50, if he so desired.  But it could be his family needs will outweigh his love of the sport.  Personally, if I were him, I would be secretly hoping that a young star emerges soon that will carry the mantle, so that he can be free to fade away from the sport and leave it in good hands.  His main competition now is aging along with him.  Someone has to rise up soon from their teens and make an impact and help to shrink the enormous space that will be left when he and the other stars of the 2000's finally hang up their racquets.   

Respectfully,
masterclass