I was just reading this morning an archaeological report about a 14th century cemetery dug up somewhere in the Balkan area. Around 40% of the skeletons belonged to children aged 0 to 7, while out of the rest no skeleton was found having belonged to a person older than 60. In the following 2 centuries the situation got slightly better, as the percentage of children 0-7 decreased to ~30%, and they were able to find a few skeletons that had lived beyond 60.
The point I'm trying to make is that we tend to very easily forget that we've come a really long way, but these things take time and they don't involve only science (the fact that the area I was studying was ravaged by the Ottoman expansion definitely had an impact on how long the people in the Balkans lived, as do today's not so healthy diets for most of the Western-populations). This is why I think that making bold and unsubstantiated predictions such as "in 20 years' time we will have reached indefinite lifespans" doesn't really get us anywhere, it only helps confusing us.
The point I'm trying to make is that we tend to very easily forget that we've come a really long way, but these things take time and they don't involve only science (the fact that the area I was studying was ravaged by the Ottoman expansion definitely had an impact on how long the people in the Balkans lived, as do today's not so healthy diets for most of the Western-populations). This is why I think that making bold and unsubstantiated predictions such as "in 20 years' time we will have reached indefinite lifespans" doesn't really get us anywhere, it only helps confusing us.