@farmerman,
Not that much, FM.
I follow the BLS data pretty closely and know a fair amount about the numbers. The size of the "Labor Force" increases by new workers (notably young) and decreases by newly retired people as well as people who go back to school or decide to become stay-at-home parents.
The rule of thumb is that we need 200K new jobs each month to keep up with population growth. I don't think that the decline in the labor force participation rate is a significant factor regarding unemployment rates , but...
I do believe that the demographics are a problem. We are an aging population. That is an issue that needs to be addressed.