Technically we already came up with a solution to "force" people to save for retirement. It's Social Security. Unfortunately the economics of the 1930s don't work quite as well these days (people living decades longer and the base of workers shrinking instead of growing, families no longer caring for their parents, etc...).

It is really sad to hear my friends in there 30's saying they haven't started saving for retirement yet, it's so hard to convince people to do this because it's "someday" money, and people like to see instant results.