Nice job talking about telomere lengthening and telomerase. Research indicates as you said that we might be able to use this idea at some point to extend further our lifespans, or reverse the outward appearance of aging. However DNA replication during cellular division is not an error free process. Immortality would necessitate us coming up with a way to not accumulate any mutations, but also as you stated doing that would limit our ability to adapt to new conditions (biologically).
It's a complicated and multifaceted problem to tackle, and a quite interesting thought experiment!
Yes, thanks for pointing out the importance of mutations (but this time I just wanted to focus on one of the reasons which cause our aging, so that the article wouldn't become too long. :)
Mutations are indeed of unbelievable prominence, not only because they damage one single organism while it is aging but also because without them we would not exist at all (the concept of evolution wouldn't work anymore).