The first and foremost cause of our societal problems today are our own people. I am not (primarily) talking politics here. I am going to let that one sink in for a while now............
Okay, check the unemployment rates in Germany and Holland in the last 2 decades, and specifically today because today we can make changes.
I wont beat around the bush with you: Shot term thinking companies are already screaming bloody murder again about the lack of good employees now and in the forseeable future. Already they are talking more immigration, regardless the present issues in society. Those silly cretins.
I say the employers should make good use of the vast army of unemployed first (
train them fcol !! It's not as if most jobs are as tough as job descriptions would suggest) and cut very heavy on the (unemployment) social welfare to get the lazy bums among the number of unemployed back to work (for money). They lose their houses when they'd refuse to cooperate ? Good ! We have a shortage of houses, so working people can move into their houses.
In short, if we would use our present labor potential wiser, there would not be so much need for immigrants (of whom almost half soon ends up unemployed or 'disabled' anyway

)
And must I remind you our world is still getting more and more technologized every day ? It's an irreversible process. And internet speeded it up. I foresee a not so distant future (can take 3 or more generations still, depending on world affairs; after all, everything is interconnected) in which actual smart robots have actually taken over a great (like 60%) part of the service business people do today, let alone in factories. I forsee a western society in which leasure will become the main thing. Yes indeed.
Economic principles will get a whole new meaning. Distribution of money will be different. It's ironic and perhaps scary to some but that way we'll be heading to a sort of economic communism lead by a relatively small elite of rulers (we will be made to believe it's still democracy) but without the totalitarian regime.
Anyway, IMO there's no more immigration needed in the next 10 years if we now change our social welfare system drastically and thus actually motivate many unemployed to get back to work plus at the same time order companies to hire unemployed of all ages, and reward/compensate them i.e. by lower taxes on their wages. For sure saves alot of money compared to the costs of immigration and the pointless integration of many muslims.