Let's see how we handle the incoming retirement issues, that'll give us a good indication (less workers, more retired people pretty much everywhere in the west, peaking in the next few decades).
Living long won't help much if it just means more people consuming our limited natural resources and weighting on our social infrastructure. At any rate most country would shift their retirement age accordingly and life would be the same but longer, I fail to see the appeal of that (albeit it's the ultimate realization of our "us vs nature" western mentality)
We should figure how to live well before we try to live longer, and we still have some things we're nowhere close to figure out (energy, pollution, retirement, increasing pop, &c.)
But all of that only applies if everyone has access to this tech, which I doubt. Most likely it will be a "cure" for the rich.
Seems to me that scientists are working toward goals that kind of look nice on paper (curing aging, genetic modifications, &c.) without stopping even one second and thinking about the moral/social/economical consequences down the line.
As for "only the rich" there are only two kinds of tech roll outs - cheaper alternatives to the existing or for the rich first. The previous while impactful tends to be less groundbreaking by definition because it isn't anything "novel". The latter is how it always has been.
We always here "but what about the consequences" but I have yet to hear a proper forecast. Which means it ammounts to stopping development for imaginary fears, pointless. The time to stop is if there are problems in testing /after it actually exists/.
It is one thing to say cancel carbon nanotube body armor or structural components due to being too carcinogenic - it is another to stop development for fear it will somehow create a new ice age, grey goo, or similar.
Thinking longer-term, it's that plus being restricted to a single planet.
Before anyone says being multi-planetary is a pipe dream, it's historically true that what ends up happening in the longer-term tends to always to be something that would have seemed ridiculous and unrealistic at the time.
Of course, there's all sorts of questions here of the practicalities (eg costs) and the timeline (eg life extension could happen well before being multi planetary).
My primary point is only that it's not necessarily true that death will always be the only thing keeping the population in check.
Generally as with any powerful new tech, inventors/scientists fail to anticipate worst possible usage for it, which is how it will be (also) used.
There would be no way to anyhow regulate it, people would go to great lengths to get it (just look how some are OK with driving animal species extinct just to get potence medicine which is proved to be not working).
Don't get me wrong, I don't think we can avoid it, but it will bring some nasty consequences before it will become a net gain for mankind.
Unless in an aging-free world, for some reason non-psychopaths are more likely to give their power to psychopaths than the other way round, I think we don't need to worry.
Many medications stay expensive because not big enough number of people are affected. Also don't think U.S. only: how do you stop people from going to China to get the cheap (but well tested) copy of a medication?
If we manage to extend the expected (or even just possible) generic lifespan of normal people - that will be one of the best promoters of environment-thinking of normal population. Because suddenly the choices they make today become very real in terms of impact on the environment in the next 50-100-200 years, because there is a good change that this same person is going to be living at that time.
Even if we lived 120 years in average, do you think the game would change a lot, I don't. I don't see drastic changes in young people today, yet they'll most likely be alive in 60-70 years. And for argument's sake, even if it does we still end up with much more people living on the same resource limited planet at the same time.
You can already bump your life expectancy (and end life quality) quite a lot by eating health, exercising, quitting drinking/smoking. Most people don't do it because it's too much effort and "that's not life", again individualism/short sightedness.
We need a cure for laziness / individualism, then, maybe, we can start talking considering longevity.
This is exactly the reason these scientists are focusing on genetic and other medical ways to increase lifespan, which are going to be packaged in products that can be used without effort. One might say what they want about people not wanting to expend unnecessary effort, one might call it lazy or just smart, or a drive of progress, it doesn't matter. The fact is if you give people a method that requries less effort, more people will use it. Thus we will have a greater general effect on the population with these methods.
Giving lazy people the opportunity to continue living lazily longer while ravaging the planet ? Welcome to transhumanists paradise I guess.
Then there's also other (more economical, but you could say that's caused by psychology as well) reasons, such as tragedy of the commons.
People fearing flying more than driving are not afraid of the relative chances of dying (which are low either way). They are afraid of the feeling and experience of spending long time in a falling plane knowing that you are going to die, being stuck in one seat and not being able to do anything about it. This does not happen when you are driving, if there is an accident, you usually either die instantly or in some rare cases receive some injuries, but at least then you can lie at the site of the accident and hope that medics will come. It's not the same as being stuck in a box for 10s of minutes knowing you are most likely about to crash to a painful death. You have to spend time in that experience, to feel it, in a completely hopeless state. That's why people afraid of flying, not because of some statistics.
Only 29% of Americans over 55 think climate change will pose a serious threat in their lifetime :(
In fact, the headline stat of that linked survey is "56% of Americans over 55 worry a great deal about global warming".
This is also encouraging:
"Gazette: Are there regulatory hurdles? When we've spoken in the past, you've mentioned that the FDA considers aging a natural process and therefore won't approve drugs to treat it.
Sinclair: I've been part of a group that talked with the FDA, and they are willing and also quite enthusiastic about considering a change that defines aging as a disease."