it will be very difficult to maintain the economically active population over total population ratio constant, you need a corresponding increase of productivity to offset the increased burden over the few working...

Right now in Europe and the US we have boatloads of people sitting around without jobs. How does it make sense to import more people to compete for the few jobs that are left? Automation means you need a smaller percentage of working people to maintain society. We can't figure out what to do with the people we have.

Although terrible for the affected, in the US the unemployment right now is 5%, hardly a catastrophe. 10% average in Europe is not horrible. If you take Spain (24%) or Greece (26%) yes, is bad, but is not sustainable and most probably things will improve in a few years... but I'm talking about decades of population reduction.

>Although terrible for the affected, in the US the unemployment right now is 5%...

U3 is a fanciful number, both because people are using disability insurance as a way to collect benefits indefinitely and because once you give up looking for a job you don't count as unemployed. The US has the lowest labor force participation rate in decades.