Good overview, masterclass--not much to quibble with.
I see Novak (and Andy and Stan) as having a window before two factors coalesce: Father Time catches up, and "Gen Next" comes more fully into its own. A bit on both:
First, Father Time. Very few Slams are won after the 30th birthday, and both Novak and Andy have only one more Slam chance before they turn 30. Of the 195 Slams played in the Open Era, 21 were won by 30+ year olds, so 10.7%. Of those 21 Slams, eight were won by Ken Rosewall and Rod Laver (four each) in a very different era; add in Andres Gimeno's 1972 French Open title at age 35, and all of a sudden we have only 12 Slam titles by 30+ year olds in the last 178 Slams, or 6.7%.
It really changes with the time. Between Andre Agassi's last Slam in 2003 at age 32 and Roger's last (so far) in 2012 at age 30, the oldest Slam winner was 28 years old (Roger in 2010). Between Andres Gomez in 1990 and Petr Korda in 1998, it was the same--only one 28 year old: Boris Becker in 1996. But this could be because greats travel in packs, or cohorts, and the age of Slam winners has at least as much to do with how old the current greats are as it does with changes in the game.
We are in an unusual era because the dominant generation is in its late 20s to early 30s, while the generation that is in it's mid-20s and should be dominant is a particularly weak one. There's a real gap in talent with no Slam winners in birth years 1989 and later, although Thiem (93) and Pouille (94) could shrink that window if they take further steps forward. And of course Kei (89) and Milos (90) are still very much in their primes.
Anyhow, as you and others (including myself) have stated, Father Time's impact on Novak (and Andy) is lessened by this. In other words, their declines will be softened by weak competition in the generation that should be holding the reins of the tour.
OK, now for Gen Next. The only player under age 24 that seems vaguely ready to challenge at a Slam, and then probably only at the French Open, is Dominic Thiem, who just turned 23 years old. Maybe he'll take a step further next year and be a serious challenger, but he still needs to prove that he's a step above the other second tier players, and he hasn't yet done that. I'm not sure I quite see it from Lucas Pouille (22) yet, but he could challenge for a spot in the top 10 next year. Nick Kyrgios (21) is also close, but has mental issues. I don't see any other players in that "ripe" range of 21-24ish that are ready to challenge.
Looking a bit younger and we have 19-year olds Alex Zverev, Borna Coric and Josh Donaldson. Of the three, Zverev is the only one that looks like a future Slam winner. Coric looks like the type of guy that will max out in the lower half of the top 20, and Donaldson maybe not even that (although his recent play has been promising).
A bit younger and we have 18-year olds Taylor Fritz, Frances Tiafoe, Stefan Kozlov, Duck Hee Lee, and Andrey Rublev. Fritz is the most promising and had a good rise earlier this year, but has stagnated--but at least held his ground--for six months or so. He could take another big step forward next year, but probably not to Slam contention; I see him as about a year behind Alex Zverev, so for next year the top 20 might be a good goal, with 2018 being possible Slam contention. The others are further behind.
And then we have 17-year olds Denis Shapovalov, Casper Ruud, and 16-year old Felix Auger Aliassime. These guys are several years away but worth keeping an eye on.
So looking at Gen Next as a whole, they will continue to get better and better but I don't see a real "swell" until 2019-20. Maybe Thiem, Pouille, Kyrgios and possibly Zverev challenge next year, and maybe Fritz joins them in 2018, but it isn't until 2019 or so that I see these guys really starting to reach for that baton.
So that gives a nice window of 2017-18 that Novak, Andy, and Stan have a relatively open field. There will be challengers: Cilic is still dangerous, maybe Kei or Milos or even Grigor catches fire for an entire tournament, and perhaps Rafa or Roger drink from the fountain of youth. But come 2019 or so, a whole new generation of talent will be coming more fully into it's own and, coupled with the fact that Andy and Novak turn 32 in 2019, and Stan 34, the window will narrow considerably.
:nono :angel: :cover 
