Political and social changes will have a greater effect on the future cost of health care in the United States. As pertains to political changes, no matter who wins the election, Obama or Romney, either one will have to make tough decisions (with the national debt in mind), which will more than likely cause health care costs to rise. It's just inevitable and both parties have to accept this fact.
Concerning social changes, the aging U.S. population, and the increase in life expectancy will cause health care costs to rise. More baby boomers will retire and they may live longer, which increases the likelihood of getting age-related diseases, chronic conditions, and sicknesses, as well as injuries (falls and such).
Another thing to consider, which will contribute to the rising cost of health care is the advent of superbugs. The fight against these costs considerable money in terms of antibiotics and the health care personnel involved. This is in addition to the research constantly being conducted to keep one step ahead of these superbugs.
Of course, medicinal and technological advances will contribute to rising health care costs. However, innovations in medicine and technological advances may actually help reduce costs sometimes. New medicines and technology may make health care more efficient. They may lead to the control and cures of some diseases.