I believe Mr. Murray, OBE, has maximized his skills winning the Olympics at Wimbledon, the US Open and the Wimbledon Championships the following year.
Wimbledon Champ

US Open Star

Every dog has his/her day

I think he has attained his biggest goals. Everything else is gravy now for him. Does he really need to have the relentless drive to win more and more? Only a few players in history had that mindset. I think what he does the rest of his career will depend on how well he feels physically and how much ambition he has left to do more than he already has.
If he retired today, I think he would be a happy man. All he would need is a good woman by his side (or maybe two if you include his mother). Kim Sears seems to be the front runner in that regard.
Mum and Chum

I could see Andy and Kim traveling around the world, running a tennis academy, or even a hotel, as long as they do it together. 
Casual Elegance

Mr. Andrew Barron Murray, OBE, Miss Kim Sears

Respectfully,
masterclass
I agree. That's how I see Andy too. I love watching him play, but he doesn't have the mindset of Nadal, Federer, and Nole. But, that's what attracts me to him. I like Nadal's passion, and Federer's striving for excellence, and Nole's quest to equal to rivals, but I like Andy too, for following his own path and being his own person.
Everyone has their own mind and skill set. I respect that.