I think the fact that firm control of the party is invested in a couple of people makes things easier, Zille will fire you so fast your head will spin I you start any nonsense.
The ANC used to be like that during Mandela's time, he simply told them, "we will never haves contest, Mbeki will lead the party, Cyril stop sulking, we'll fix you up with some BEE deal." Everyone was happy. When Peter Mokaba started some nonsense he dealt with him and when Holomisa got cheeky he expelled his behind.
Even Mbeki's reelection was also without any drama. What is happening with the DA simply points to the balance of forces being heavily stacked to one side, Zille to her credit has made sure things remains that way by sacrificing the growth of the party to keep herself and her inner circle firmly in control.
Wait until there is a shift and you will see, fortunately that doesn't look like it will happen in the near future.