Well, they haven't released a lot of FF lenses during the last two years, so sales cannot be good. I found the phrase in that German article weird too, unless of course, as David mentioned, Zeiss has provided Canikon with glass (isn't Schott a subsidiary of Zeiss?) or some other material we don't know about.
More likely, this was a clumsy and incorrect way of refering more broadly to DSLR-related sales. In other words, it might have been a smarter idea to invest the R&D that went into developing those Milvus lenses into a line of fast mirrorless lenses. Of course, with Cosina already having (very) fast MF lenses available at the 21, 35, 40, 50 and 75mm FL's, Zeiss better hurry, if they still want a piece of that particular cake.