It's not just English that absorbs linguistic influences from other cultures and languages. What's happening with German seems to reflect patterns that have been noted in English over the last 20-30 years, where German teens are picking up vocabulary items from Turkish in areas where there is a significant Turkish population and mixing goes on between different ethnic groups. In this report about a study from Pottsdam University, the suggestion is that it's mostly lexical features - a few words - that are picked up by German youths.
So is this similar to Multicultural London English, with a new hybrid language emerging? Or is it more like London (and maybe Birmingham and Liverpool too) in the 1980s when it was more a case of "crossing"? I suspect it's the latter, as there doesn't seem to be quite the same range of lexical, phonological and grammatical features that we see in the research of Paul Kerswill, Sue Fox and Jenny Cheshire into MLE (as seen being explained by Paul Kerswill here in a TED lecture).