Fortunately, their approach seems to take into account the fact that most people's quality of life degrade very steeply after hitting, say, 70, and aim to augment this "quality" lifespan at the same time as the "total" lifespan. Just ask Scott Adams if he would have wanted his father to live "well beyond 120".
Another important point is that the relation between children, their parents and the society they live in would be changed in ways that are hard to predict. See, the current assumption (or rather, the assumption that socially still stands but that is already shaken by the current lifespan augmentation) is that once a child is an adult, it won't be long before they will eventually see their parents either die (before…
And as you point out, healthy elders won't retire. In a lot of countries there's talk of increasing the standard retirement age from 65, where it's been for many, many decades, which is a step in the completely wrong direction, since that just accelerates the job shortage. It's no coincidence that youth unemployment is higher than ever.
I can see the bright future, but I cannot see the way forward. Every political party is about keeping the status quo, keeping the 9-to-5-and-a-mortgage going, the left/right divide is about who owns the means of production, but both are firmly set on the notion that everyone should work. There are no incentives for existing power elites to change either. They will benefit immensely from the automation improvement, because the owners get all the profits, while the employees get less and less, since there's fewer and fewer of them.
It's interesting that the work week has been stuck at 8 hours for over a century, while worker productivity has increased magnitudes.
I don't know what to do, how to change this. What political steps need to be taken?