I do not mean to suggest that it is a bad thing for people with jobs to support retired workers. In most cultures, constructive and supportive relationships exist between young and old. Parents, after all, generally support their children as they grow from infants to young adults, and often help with grandparents too. When I was a child, three of my grandparents, one widowed grandmother and a pair of grandparents, lived with us in our house. Today many younger professional couples arrange for their aging parents to move to an apartment near them, or the working couple relocate to keep an eye on them. We tend to play up the glamorous independent life of the "young professional" and you might not realize that these multi-generational families still exist in considerable numbers in America. If a government program of retirement assistance involves the young supporting the old, perhaps it is best to view it as embodying a larger and accepted principle about mutual respect between generations.
The effectiveness of such programs obviously depends on the proportion of active workers to retired workers. In countries with both expanding populations and increasing longevity, an approximate "balance" will exist between these two groups, those working and those retired. However, I think China, still the world's most populous nation, has a unique challenge. The one-child policy will obviously limit the size of the workforce in the future, while continued development and prosperity will bring better health and longer life to older people. Now, I can't possibly make a thorough study of the subject, but I am confident that smart people are looking carefully at these two trends and projecting ahead for better planning of China's retirement assistance programs.