I am currently in my late 30s and have two kids under 10. Assuming my children have kids of their own, and no sort of accident happens to them, do you think it is reasonable to assume that a middle class/upper middle class family can see their children (ie my grandkids) benefit from longevity in the next 20-30 years? At what point do you see middle class people routinely living hundreds of years (or more) in good health?