which demographic trends do you expect to have the greatest impact on health and human services delivery in the United States in the next 10 years?

Take your pick:

increasing number of senior citizens as baby boomers retire

increasing number of very elderly people as medical and health knowledge has grown

increasing number of people with diseases we thought already conquered (polio, etc.) as more documented/undocumented immigrants enter the country without the immunizations we take for granted

increasing number of children and adults with mental and learning difficulties because they were born to addicted moms

... and I'm sure there are umpteen more. You should wander around in http://www.fedstats.gov for further possibilities, specifically here:
http://www.fedstats.gov/regional.html

=)