I think the vote tomorrow is on a knife edge. The cabinet and the NEC are keeping Zuma in his position, if Zuma goes they are out, the president loses his pension and criminal charges will be instituted, Nkandla could be converted into an entertainment centre. The ANC lost the Nkandla district in a recent election rerun. I think the MP's that are unhappy with Zuma and his gang will vote against him - he will lose office and so will the cabinet, there are thus opportunities for these MP's to be elevated to MP level.
If the ANC don't take action now with this matter they don't stand a chance of winning in 2019 and then MP's will be ousted so its in their best interests to cut the cancer out now and then concentrate on improving their performance in 2019
Just my take on the situation as it is a zero sum game whichever view you support