Only certainties according to the coach before the series was Smith, Kallis and Prince (and Boucher of course), everyone else needed to score a far amount of runs. Both Amla and Gibbs haven’t after four innings whilst AB is likely to be on a hiding for nothing tomorrow with South Africa presumably only looking for quick runs, once Smith and Kallis depart. However, he should retain his place, played a significant knock in the first test whilst he was beyond unfortunate in this test with his dismissal.
The alternatives discussed before this series ranged from JP Duminy (who toured), Neil McKenzie, Boeta Dippenaar and Morne van Wyk. Although, Rudolph still has two years left with Yorkshire so he has no chance of featuring anytime soon.
If I was selector, I would give Duminy the home test series against the New Zealanders, replacing Amla but have him bat at four; get Kallis back to three and have Morne van Wyk opening instead of Gibbs.