I could be totally off-base but I can't help thinking this is Sport's BS, I certainly hope it is. Just a couple of days ago Masch told reporters in the US that he would not leave us on bad terms, something to that effect and I think he clearly knows we need him for at least another season. Him abruptly leaving regardless does not sound very plausible. That said, either way we know he is not very happy and he does want to leave, it is just a matter of when. So even if he does stay, we need to start looking for his replacement.
In the DM position we have Busquets as a starter, but he hardly has a sub, only if you consider Samper one (Roberto doesn't count in my opinion). Kimmich would be my dream signing there but it is 100% not possible so maybe we can start looking into Weigl. On the CB front it is a on-brainer, we need at least one more CB in addition to Umtiti. If Masch leaves this summer and we only sign Umtiti, we will only have three CB's, Pique, Mathieu and Umtiti (Vermaelen is just too injury-prone so I don't count him as one), and if one of them is injured God forbid, we are screwed.