You need them to assimilate; but that also requires a bit of flexibility on your part. They need to learn German, their kids need to be the bilingual diplomats; their grandchildren need to become German with a side of Syrian.
But it goes two ways; you have to accept mosques in your cities; syrian resturaunts; syrian music; and the real benefits of assimilation: a dialog where on a cultural level syrian changes german culture a little.
The most successful assimilation happens when 100 years from now; the moment when you have aspects of German culture that are Syrian and don't even realize it.
I don't mind new cultural influences but as Shroom mentioned, many of the people who come here don't seem to want to become a part of our country. They refuse anything that is not directly based on their own culture, including the language. We still have lots of older people here who migrated to Germany 50 years ago but still can't speak German - and that is because they don't have to, they live in areas with a lot of their folks and shops and rarely move out of their circles, except for going to work.
We already have a lot of mosques here and I don't have a prob with that, it's not on me to tell people what to believe, but again, building mosques didn't come with an opening-up of Islam like politicians and scientists wanted us to believe, on the contrary, the more freedom we got in our society, the more strict their belief system became, up to a point when they wanted to install Sharia courts in our cities which didn't fly even with the leftmost do-gooders but that doesn't mean they would refrain from making Sharia-style judgements within their communities. Parallel societies.
There were and still are lots of integration programs that try to get people out of their niches and into the middle of life over here, it just doesn't work, and that's because quite a few of them silently loathe and consequently reject our Western style of life that looks like the epitome of a godless life to them.
Now, not every immigrant is like that, there are many who accept the country they migrate to as their new home and try to become familiar with its customs and traditions while keeping their own cultural background in balance to their new life. These are the ones who eventually become a vital part of our society and bring in new things and ideas which is an asset for any country and its culture.
The trick is to know who is who. Those who come here to lead a normal and safe life are very welcome, those who think they can shit on us while forcing us to cater to their religious sensitivities can fuck right off as far as I'm concerned.