As I understand it, there are these filaments within the cells of the body called telomeres. Every time the cell divides, the telomeres shorten. Other things can damage the telomeres as well, such as radiation. The shorter the telomeres, the more errors pile up when copying DNA during cell division. Those errors result in less and less functional cells and the overall entropy/breakdown/aging of the body.
This Bible verse points to an average lifespan age and a "good old age" for those who are healthier/stronger/have a better lifestyle, etc. But the telomeres themselves represent a hard limit to human lifespan without modifying the human organism.
There ARE those who want to modify the human organism in order to eliminate aging. And theoretically speaking, I think it's possible to do so with technology. I just don't think that God is going to allow humanity to achieve this. Look at the Tower of Babel account. There are some human projects that God just says, "Nope, that's not going to happen" and it doesn't.
Another similar thing is the suffering of women with their cycles and childbirth. This should be technologically solvable. But it's actually a Biblical curse from God and a reminder, so I don't think it's something that there will ever be a widespread solution for.