Centenarians have been shown to have increased healthspans. They still get the same diseases as everyone else, however they get them much later in life (90s, 100s). That's all I'd want. If we can get medical science to a point where healthily living to 100 is common, then that's a win for everyone and it'll save us a ton of money. The problem is, like you said, that it's unlikely to be some miracle drug; it's going to be small routines and habits throughout your life that will require willpower and discipline, so that'll exclude a lot of people unless we restructure society in a fundamentally different way.