Life expectancy
Predicting future life expectancy is difficult. In a post, Kevin Drum of Politcal Animal at shows that the actuaries have done pretty well. He quotes one as saying that privately, they expected medical tech to provide faster gains in life span. I think they, and most others, expected a greater rise from medical advances. It has turned out that human biology is more complicated than anyone expected and that early successes with antibiotics and sterile technique were extraordinary. Since then it has been hard slogging.
The huge research effort into biology *will* pay off, but when? I expect it will pay off any time now (in a decade or two). Many different approaches to cancer treatment are being tried, I expect one will succeed. Heart disease can be fought both with biological approaches and with mechanical/electronics tech approaches
The other big factors are culture, business and the environment. US culture has become unhealthy, with people less active. I don’t expect that to change. The industrialization of food has been unhealthy. Effort has gone into making food tasty and cheap (sugary and fatty), and to use advertising to sell people more calories and bigger portions. My guess is that the food business will start pushing healthier food across the board. Healthy food will grow from the niche market it is now to become the norm.
The environment has had its ups (pollution controls) and downs (leaded gas, smog). I expect it will get worse, with overcrowding being the dominant factor. On the local side, I expect pollution will slowly get worse. On the global side, I expect that catastrophes will start popping up (oil scarcity, overfishing, lack of water, climate change, war, etc). Some will affect life in the US directly and others indirectly by slowing or reversing economic growth around the world.
How do all these factors integrate? I have no idea.