Here are a few more data points and comparisons for what they are worth:
Stan Wawrinka is a bit of an anomaly, 31+ years old, over 2 years older than Novak, but he has only played 677 matches - 200 matches less, about 2-3 years worth of matches, or to put it another way, about the same # of matches that Novak had when he lost to Stan at the 2014 Australian Open, or when Federer won at 2007 Basel not long after winning his 12th major at the 2007 US Open!
As stated previously, Novak had played 879 matches when he won his 12th this year at Roland Garros. Roger Federer had played 850 matches when he beat Murray at the 2010 Australian Open for his 16th major. But then he had a dry spell as Nadal and Djokovic gobbled up all the majors from RG 2010 to RG 2012, and finally won his 17th at Wimbledon 2012 in his 1045th match which I believe is the highest number of matches to win a major of any player since the early Open Era and Rosewall.
Novak has now played 894 matches, but his advantage is that there are no 24 to 26 year old players the likes of Nadal and himself as Roger had between RG 2010 - RG 2012. However, some tough players capable of winning majors are still in the mix, like Murray (780 matches), Wawrinka, Cilic (578 matches), and the underplayed due to injury Del Potro (only 474 matches played), and perhaps some younger players might finally rise up in the next few months. We just never know.
Respectfully,
masterclass