I agree - South Africa has plenty of batting depth at ODI level.  Obviously Amla and de Villiers are the best two batsmen, but even without them they have a huge amount of quality in the top order.

Hard to read too much into the NZ vs SA ODI series with NZ missing our two (perhaps 3 if you include Ryder) best ODI batsmen (Williamson and Taylor), Guptill so woefully out of form, and  the experimentation with the bowling lineup.  South Africa have won the first two matches incredibly comfortably.  Probably the biggest positive from a NZ perspective is the return of Vettori (who has been accurate - if not threatening).