A lot of us do not believe for one moment they will find work, usefully integrate, "settle down" or learn to be any more than passable in their hosts language. I foresee them ostracising their hosts, or worse, living in ghettos amid their own, continuing the crime that is endemic in many of their lifestyles, and possibly becoming radicalised and turning against their benefactors. It's a well trodden path and I see no reason anything will be changed with far greater numbers of them in Europe. I see it being far worse, in fact, far far worse.
Your rosy picture of adaptation and "settling down" sounds fantasy in fact.
Seriously? This is very hard work.
Some may very well do what you say - as a result they won't be eligible for citizenship and therefore cannot simply wander in the UK at will!
How can you be missing the point so massively here?
Only those who integrated, learn the language and hold down jobs can become German citizens. And once they've bothered to do all that they'll be quite settled in Germany anyway!
If the idea of any of them 'settling down' is fantasy then so to is the idea of any of them being able to legally come to the UK. So the issue is what? We need a Brexit to save us from.. what?