You do know that Cruyff shared an era with Beckenbauer, that Platini joined Juve from Saint-Etienne being 27 y/o and won his first one with 28 and only played two more seasons after his last Ballon d'Or, or that Van Basten basically retired months before his 3rd one being 29, right?.
I doubt Cristiano or Leo would manage to be candidates to the trophy for 10 seasons if they played in the 70's, 80's or even the 90's. First for injury reasons (from boots, to the grass and most importantly medicine) and second because it was harder to assemble super teams when they were subject to the 3 foreigner rules, either you struck gold with a golden generation (like the Germans or Milan with the 3 dutchs) or Real would have a hard time to decide which 2 to keep from Navas, Pepe, Marcelo, Casemiro, Modric, Kroos, Bale, Benzema or James to surround Ronaldo. Same with Pep's Barça if they had to choose 2 foreigners from Alves, Marquez, Abidal, Toure, Eto'o and Henry.
If things go well, we might have a duel between Ronaldo and Messi for even 4 more years, Ibra peaked stat-wise being 34 and with 16 seasons of profesional football on his legs, so I wouldn't discard milking ~3 more years from Ronaldo (15th pro season) being top 3 in the Ballon d'Or.