Hughes et al (2015) -- Opportunities and challenges of a world with negligible senescence

We estimate that rollout of such an intervention on a widespread basis would be infeasible even in the wealthiest countries if the initial price were set at $10,000 per year of healthy life added. At the price of $5000 per added healthy-life-year that we assumed through much of this paper, the initial financial burdens would be manageable for wealthy countries and would, over time, yield considerable reductions in disease-related expenditures that would more than offset the cost of the intervention. Yet poor and also middle-income countries would struggle to finance such an intervention even if, as we assumed, up to 95% of the costs in the poorest countries were defrayed through price reductions of the sort that have recently been observed for high-impact antiretroviral treatments.

[...]

Finally, our results point to perhaps the greatest challenge facing a world of negligible senescence, those relating to the sustainability of our natural resources and biosphere. Given widespread concern that our economic way of life is already unsustainable, the potential addition of billions of people would concern many, especially given that this population (in the absence of negative feedbacks from environmental constraints) would see a GDP per capita 30% above the already substantial economic growth built into our Base Case.

Making a pretty good case that "negligible senesence" (read as "extropian immortalism"), even if it turns out to be possible, would be a total disaster for us as a species.

(Not that any of its biggest advocates give a shit about us as a species, of course.)