I mean, you can imagine some kind of intervention where you just replace everything, I suppose, but in the real world the mortality curves are exponential with age and any fixed amount of reduction gets eaten up pretty fast. Totally worth trying to keep people healthy I think, but they'll still die.
You’re falling out of an infinitely tall tree and when you hit a branch you die. Sawing off a finite number of branches means you fall farther, but there’s infinitely many of them!
I suspect people who don't agree with this implicitly don't believe there are actually an infinite number of branches. And maybe there aren't, but I think as an approximation for any technology we are going to have in the relevant future, infinity is correct.