In an article I read to day there is an equation used to try and predict what your domestic workforce equation looks like.
The report offers the Aging/Work force Equation: global aging + country/region factors + policy levers + wildcards = work force outcomes.
They also offer 7 implications relating to this scenario.

Domestic supplies of labor will decline.
o Aging will “double whammy” the high-skilled worker supply.
o The global “Battle for Talent” will intensify.
o Indigenous supply of low-skilled workers will decrease.
o Manufacturing firms locate where there are less labor shortages.
o Globalization of human resources.
o Efforts to substitute capital and technology for labor.
Read the complete article here: http://www.salemnews.net/news/story/0723202006_new07brownfield.asp