To summarize:

Exchange rate-driven deflation will force the SNB's hand, we expect this to be in the form of a 50bps cut (SNB rate to minus 25bps). The underlying inflation picture is more dire than is commonly assumed, justifying a return to negative rates. Money market considerations make a cut of 25bps predicted by consensus expectations unlikely. A cut to zero comes with the risk of disrupting money market stability. Namely, significantly reduce interbank repo activity, which would undermine the credibility of SARON as the SNB's reference rate.