Most of developed economies dont need blue collar foreign labor in the future. Some dont even need it now. There are no industries in uk or france and this labor role is mostly to suppress wages (we ve seen it with brexit and english truck drivers) . For industrial nations like germany before they shot themselves you do need this labor until robots and automation makes them obsolete. Way before 50years and then being a nation with low immigration is becoming a key advantage for a country cohesion and future. Finally every country at 25% youth unemployment (like france and spain) shoould block all immigration beside highly skilled immigrants