The International Monetary Fund talks about the positive impact of immigration on workforces of developed countries:
Migration can relieve the strain of population aging and contribute to other long-term gains, such as higher growth and productivity. Net migration accounts for roughly half of the population growth in advanced economies over the past three decades….dramatic shifts in demographic structure projected in advanced economies could overwhelm the ability of policies to offset the forces of aging.
Aggregate participation will eventually decline and that the participation of older workers must rise significantly to stem the decline in aggregate participation. Unless technology delivers offsetting productivity gains, these findings highlight the need for many advanced economies to rethink immigration policies to boost their labor supply…Although receiving migrants can pose challenges, potentially prompting a political backlash, it can also be a boon for host countries.