[Udo]

That's a huge "what if", on top of what's already an impossible-to-predict situation. But if we're going to entertain this, we should also factor in the other circumstances that are likely to come with this scenario:

I spent a chunk of my life adjacent to bio/med research and my conclusion is radical life extension by purely biological means will probably remain unfeasible. Genetically, we're millions of years worth of horribly interdependent spaghetti code, there is no fixing this mess. So - barring the option to upload yourself to silicon - death won't be obsolete by 2065.

However we might see some very, very moderate increases in life expectancy across the board, even in comparatively poor nations, as long as they're not living in abject poverty. This would be cause for concern, but data from industrialized nations suggest a major regression in births once a population becomes (somewhat) wealthy and healthy.

The desire to procreate boundlessly may very well be a deep-seated instinct triggered by living in precarious environments. If dying slows down, it's because of improved living standards and medical care, the same things that stop over-procreation.

It seems to me that in order to control Earth's population, we need to address poverty, which incidentally would solve a huge slew of other humanitarian and ecological problems.

[kobeya]

First, I don't think you are adequately compensating for the availability of new technologies, such as medical molecular nanotechnology, which we will certainly have by 2065. The entire approach to medicine that we use now is likely to be obsoleted in that time frame, leading to the eradication of most terminal diseases.

Second, one doesn't have to eliminate biological death entirely to muck up those forecasts. We know from super-centenarians that those who are lucky enough to not suffer any life threatening conditions nevertheless kick the bucket around age 120. Even if that's not fixed by 2065, it's almost double the average life expectancy and that is not factored at all into the OP's calculations.

Third, birthrates are currently constrained by menopause in women. Most women don't have more than a few children in the developed world because they are biologically incapable of having more. And although men have the capability to have "2nd families" (with another woman later in life after their previous children are grown), women do not. Defeating/controlling menopause is therefore more likely to result in either larger families, women choosing to have a second family at a later stage in life, or women who would have otherwise missed their chance having a family at all. Again, fertility advances are not factored into the OP's calculations.

Thus although I could argue that biological immortality is not "unfeasible", I don't need to. The OP has failed to factor in reasons why the death rate will go down and the birth rate will go up, making his charts too conservative.

[valleyer]

Whoa, I really like your spaghetti code analogy.

To me, it also means that the "upload to silicon" stage is unlikely, because it probably requires understanding and reimplementing (possibly bug-for-bug, in some places) the original, for, uh, carbon compatibility. (And if we really understood it that well, we'd probably just fix the original...)