quality of life = continuation of life? or, are we to feel full of vigor up until the moment of death? (although, i suppose that is already the case for some unlucky people). otherwise, there's bound to be a gradual decline. is this technology going to lengthen that gradation (vigor->decline->decline->disease->stemCells->vigor->decline->etc->death), or effectively accelerate it (vigor->death).
or, if we cure the common illnesses that we encounter later in life, then what is it that'll kill us? i guess our quest to cure "common illnesses that we encounter later in life" has enabled our current longevity, but how much more can we eek out?
(not to mention the sociological implications of paying for longevity, which i suppose is something that's been a factor since wealth)
sorry, i'm mostly thinking out-loud here. i'm sure smarter people have thought out responses to these questions related to life-extension already.