Originally Posted by No1e
80s: Lendl with 270 weeks, and many doubted there would ever be someone to overtaking him; and then we have...
90s: Sampras with 286 weeks, and many doubted there would ever be someone overtaking him; and then we have...
2000s to early 2010s: Federer with 300+ weeks.
Moral of the story: don't doubt, just wait and see. There will always be someone else taking over. I think the person who has the most potential to do it is Novak Djokovic, followed by Nadal.
I'd say the person with the most potential to do it is someone in the future, who's not 25+ and will come in to dominate the game after Federer, Nadal, Djokovic, and Murray are all 30+ or retired.