If and when it does become an issue, it will likely be one born of success in other areas. For instance, if a majority of people are getting this life extension treatment, that implies the gap between the haves and have-nots will be virtually non-existent, at least for this particular area.
That gap is pretty big right now, despite historically unprecedented improvements. For it to decrease so that most people can afford treatment that gives them an active life-expectancy of (for example) a hundred years would require a lot
of things to be very different than they are now.
Thomas Malthus warned about the basic problem (http://en.wikipedia.org/wiki/Malthusian_growth_model
) over 300 years ago. The tipping point may have already been passed; our current civilization and the technology that supports it is very resource-intensive. That can't go on indefinitely.
I think of myself as cautiously optimistic about the issue (arguably because I've never had to live in a poor developing nation). I believe the human race will survive and eventually surpass its current state of development through a combination of ingenuity, rationality (born mostly of desperation, but still) and of course self-interest. That transition will definitely not be easy, pleasant or cheap
, but I believe we can do it.