Fiero, I think the point is that Roger has been the most successful 35+ year old since Ken Rosewall. No one in the last 50 years--the entire Open Era--has been close to as good at that age, and really at any age over about 32. That is impressive.
As for Roger and Rafa, who knows. I counted both out and they both won three more Slams. A lot of people were counting Novak out, and I said "If Roger and Rafa can do it, why not Novak?" And here we are.
That said, I do see us now in Novak's Indian Summer, just as 2017 and the first half of 2018 was Fedal. Maybe Novak's last through 2019 and he wins 3-4 Slams, finishing with 16-17. But at some point someone will break through. Maybe Sascha, maybe Thiem at RG, maybe Tsitsipas or Shapo (although probably not Shapo until 2020 or 2021).
But yeah, I think Novak will win a few more and finish with at least 16. Rafa...who knows. If he's healthy he's still the favorite at RG next year, but only by a hair over Novak and Thiem needs to be taken seriously. Roger probably won't win AO again with Novak back. He probably only as one more chance at a Slam, Wimbledon next year, and will have to peak just right. But I do think he's done winning Slams. He'll get his 100+ titles but may not catch Connors.
Actually, Novak's resurgence probably protects Roger's Slam record. I can't see Rafa winning another Slam or two with Novak around, and maybe not even that.
And yeah, by this time next year I think Next Gen will break through, either at Wimbledon or the USO.