I don't think that his thirst for majors has been quenched at all. I think in the light of what we know post yesterday, he has simply crashed mentally and physically. A mini breakdown if you like.
Let's look at the past 15 months.
July 2012 - he suffers the most devastating loss of his career at the hands of Federer at Wimbledon. The lowest of the low.
August 2012 - He defeats the self same Federer, on the self same court to win the Olympic Gold. The highest of the high, coupled with all the intense emotion of the home Olympic games.
September 2012 - He defeats the World No 1, to achieve his greatest ambition. The highest of the high.
Jan 2013 - He discovers one of his closest friends has got cancer. He deals with the major high of beating Federer in a Grand Slam for the first time, and is runner up in another Grand Slam final.
March 2013 - He wins his first Masters in over a year - No 9 (remind me again how many Del Potro and Berdych have got between them - 1.
March 2013 to May 2013 - He has to contend with a back injury, having to miss the French Open, and a really crappy clay court season because of the injury.
June 2013 - The grass court season, with all the attendant pressure the nation starts to put on him, ever year. He delivers magnificently by wining Queen's, together with all the emotion of the Rally for Cancer.
July 2013 - He achieves another lifetime's ambition, and delivers to a desperate nation the trophy it has been craving for the past 77 years. As it was put so eloquently "becoming the first Brit to win Wimbledon in short trousers".
Even on holiday he can't get a break the press are still hounding him.
August 2013 - the first cracks start to appear as demonstrated by his performances at Toronto and Cincinnati.
Sept 2013 - He crashes at the US Open.
Murray has always appeared to be a complex soul, not surprising given his history. He has obviously been struggling with it all. The only really puzzling thing is how the heck he has managed to keep it together for as long as he has. As people have said, it took Djokovic 3 years to get his second slam. Del Potro hasn't managed it yet. Murray pulled it off less than a year later.
Rather than condemning the lad we should all be feeling wassaks for not having the sense to realise what he was going through. Hopefully the lad can be given some time to get his head together, and get some major league TLC from his nearest and dearest. If he plays Davies Cup great, it might do him good to spend some time as part of a team again. If he can't manage it fine. He needs time to retrench, retreat and rearm - mentally as well as physically. The lad will return one way or another. I doubt he is quite ready to throw in the towel yet.
Great posting!! Thanks for doing the research, I think we all needed to read it.