Sadly you may be right. Obviously, it's going to be extremely difficult for any rival fighters in any generation to be as popular and iconic as Ali and Frazier, but the least they can do is clear out their division and then fight each other putting their 0's on the line. Guys just don't want to do that nowadays and would rather argue on Twitter for 5 years until the fight has little historical meaning when they're past their best.
It was a unique circumstance with the champion, Ali, being forced out of the sport and Frazier then becoming champion and the de facto interim guy until Ali was able to come back (which of course was in question for some time while he was exiled) so you literally had two guys with legit claims at being THE champ. And, as noted, the title of heavyweight champion of the world was a revered accomplishment recognized across all nations and all sporting fans as being probably the pinnacle of world sport — the athlete at the top of the mountain as far as universal recognition and respect and reverence. That can never happen again.
I agree. There were many unique circumstances that made the fight of the century THE fight of the century. I'm just saying part of the reason it was such a big event is because the two best fighters in the world WANTED to fight each other and were not afraid to lose their 0. Ali and Frazier didn't let their fight "build up" or "marinate" for 4-5 years with tons of cherry picking and back and forth sneak dissing. They fought as soon as they were able to--3 times. It's easier to pull wisdom teeth than to get some of these guys to get in the ring nowadays.
FOTC, closely followed by the Rumble in the Jungle. Schmeling's victory over Louis is up there but not quite on a par, in my view - and I only make a distinction based on what was at stake in each case, at the time, i.e. Louis/Schmeling (I) was seen as a routine, non-title, build-up fight for Louis; whereas, the significance of FOTC was that it would decide, which of the two men - both with a legitimate claim to being called the best in the world - was THE best in the world, at that time.
I think Foreman only would've been champion for a year or two more, if not less, most likely losing to Young, Lyle, or Bugner. Ali could've regained the championship at that point.
Foreman's win over Moorer is up there, as should be Liston V Ali 1. Schmeling's win over Louis is probably my pick of the bunch. It's well forgotten, and I all too often hear excuses for Louis, but the reality is Schmeling was already past his peak but still defeated the seemingly unstoppable Louis by fighting one of the most wonderful, technically brilliant fights ever recorded. All of these are great choices,