What does this mean?
There are two very different classes of things present here.
One class of impacts on life expectancy are risks to life that are external to us – things that happen to us.
Another class of impacts are the risks to life from our particular biochemistry.
It became clear to me in 1974 that the default mode for cellular life is indefinite life – as per most bacteria and many other simple organisms (like hydra). Such cells are not immortal as such, but do not appear to suffer any significant loss of function with age. Our germ line appear to operate in this mode – we are part of a continuum of life some 4 billion years old – as is everything else alive.
The fact that our somatic cells do have degrading capabilities must be the result of some genetically controlled mechanism (because our germ line doesn’t – same genetics).
Thus, when we understand that mechanism sufficiently, it does appear possible that we will be able to extend lifespans indefinitely.
This is unlikely to be a gradual thing, much more likely to be a quantum thing, a single step change (or at least a close approximation thereto).
All outcomes to date have been on the external factors.
We have much more we can do there, and the step change above will effectively remove the asymptote currently on the graph, and provide significant impetus to further research on reduction of other risk factors.