Emily
Fully agree that she can continue to make a great contribution by continuing to be dynamic and get things done - as a back-room technocrat.

To most South Africans (80% are black) she comes across as arrogant, opinionated and unrepentent for whatever hurt or harm her comments make, whether they are distorted, misunderstood or not.
The same applied to Tony Leon.

In the same way that Zuma is pretty much universally reviled and despised by most DA supporters, Zille is strongly disliked by a significant proportion of non ANC supporting black people.

Maimane is the future and Zille is the past for the DA.

Under Maimane the DA has the possibility of growing its support to the extent that the ANC can be unseated.
Under Zille, the DA has reached a ceiling.
None of this in any way should be construed as ignoring the temendous work that Zille has done for the DA and her many achievements.

As for Zuma's age, that is irrelevant - he is no more useless now than he was when he was 30!