The most recent one is the head of the German Institute for Economic Research, professor Marcel Fratzscher. In his recent interview he "warns of a wave of bankruptcies in German companies".
Just as I said before, the biggest challenge German economy is going to face from now on is bankruptcy and the fleeing capital since due to competition the products made inside Germany would be a lot more expensive than same product made elsewhere. Consequently they would either be forced to shut down or move everything abroad, in either case lots of regular Germans will lose their jobs.
BTW, that will sink the European Union. Because after the Brexit, Germany was the main "donor" nation within the EU. Southern nations such as Italy and Greece are largely dependent on fund outflows from Germany. In case the revenue surplus vanishes in Germany, then in the long term EU will fail to exist. The model of richer northern countries such as Germany subsidizing poorer southern nations such as Italy will be difficult to maintain. Or they can survive by increasing the taxes even further, which is like a double edged sword.