I am inclined to believe that there are potential workers at the margins of the labor market who will return as the recovery continues, the labor market tightens further and wages increase. The U.S. participation rate for workers in the 25–54 age group is now below those of most other advanced economies, including the U.K., France and Germany, for example.
The number of part-time workers who want full time work remains above pre-crisis levels, which suggests that there may be some remaining slack there as well. In addition, we should expect to see stronger wage increases as the labor market tightens.