@TheMagpulPone
It is already unsustainable.
But, lets keep some things in mind. First, the technology will be pretty much exclusive to the first world for many years. While leading experts believe that the average Westerner will benefit (as it is predicted to be fairly cheap) places with a much more rapidly growing population (read, poorer) will likely not have access to it.
Secondly, if you can extend your lifespan by 50, 60+ years, and still be healthy and fit as a fiddle…then there is no impetus to breed early and often. You’d see the average child bearing age shoot up dramatically.
Thirdly, now that we would be living into the greater future…suddenly a lot more people are going to see sustainability and climate change as important. It will no longer be “our grandkids problem”.
And lastly, if our experts can live longer, and focus on their work more, space colonies may not be far off.