Well when Cilic/Delpo could win a slam, and Stan/Murray could win 3 each in the Big3 era, i find it strange that players born between 89 and 95 couldnt win a single one (Thiem won it when Big3 were injured/disqualified)Change of Guard could not happen because of Big 3.
Federer dipped after 2017.
Nadal dipped after 2019.
Novak is yet to take a dip, though his dip will also come in 1-2 years.
All blame on people born from 1988 till 1996 but then Thiem-DImitrov could not step up as their age difference was too close to Djokodal, Federer also was a beast in his own way till his late 30s.
These 3 guys are the greatest of all time for a reason.