The world as it is today is not ready for people who wouldn't age at all. Such kind of development will bring along deep social and political changes, not to mention conflicts.
Let's say some big corporation comes up with a product that you inject in yourself only once, and it'll fill your body with little nanodudes that'll reproduce themselves and keep fixing molecular and celular damage as they find it (something like the blood worms in Blade of the Immortal, but not as nasty). As a bonus, you get faster healing from wounds and diceases, throwing cancer and cardiac problems out from the window.
Such thing would surely cost bollocks of money, no matter how it actually costs to produce. That would make the barrier between the rich and the poor (and the not-so-poor-but-far-from-rich) massive, turning the overly rich actually able to retain their richness until someone run them over with a truck.
Even if such thing were to be accessible to many, retirement policies would need to be redone (they already need, since we have more and more elder people), or scrapped entiirely (if you won't age, why stop working?). And birth control policies would need to be way more strict than the Chinese ones.