Projecting the labor force participation rate is very complicated. There are many conflicting trends that must be considered …
For those interested in the numbers, I recommend this recent article from BLS economist Mitra Toossi: Labor force projections to 2022: the labor force participation rate continues to fall
The U.S. civilian labor force—the number of people working or looking for work—has gone through substantial changes in its size and demographic composition over the last half of the 20th century. During the 1970s and 1980s, the labor force grew vigorously as women’s labor force participation rates surged and the baby-boom generation entered the labor market. However, the dynamic demographic, economic, and social forces that once spurred the level, growth, and composition of the labor force have changed and are now damping labor force growth. The labor force participation rate of women, which peaked in 1999, has been on a declining trend. In addition, instead of entering the labor force, baby boomers are retiring in large numbers and exiting the workforce. Once again, the baby-boom generation has become a generator of change, this time in its retirement. Moreover, the jobless recovery of the 2001 recession, coupled with the severe economic impact of the 2007–2009 recession, caused disruptions in the labor market. In the first 12 years of the 21st century, the growth of the population has slowed and labor force participation rates generally have declined. As a result, labor force growth also has slowed. The Bureau of Labor Statistics (BLS) projects that the next 10 years will bring about an aging labor force that is growing slowly, a declining overall labor force participation rate, and more diversity in the racial and ethnic composition of the labor force.
The U.S. labor force is projected to reach 163.5 million in 2022. The labor force is anticipated to grow by 8.5 million, an annual growth rate of 0.5 percent, over the 2012–2022 period. The growth in the labor force during 2012–2022 is projected to be smaller than in the previous 10-year period, 2002–2012, when the labor force grew by 10.1 million, a 0.7-percent annual growth rate.
There are a number of tables in the article showing the trends for various cohorts. An excellent resource!