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?
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.