My only concern for Ireland is at 31, James Lowe is possiboy looking on the start of a downward trajectory. Ireland could really have done with one of the Ulster wingers getting fit and stepping up. But this is a minor quibble, he is still very capable and deceptively fast despite rhe Zebo diet. Other than that Ireland have looked very handy all year and I will likely favour them here early in the tournament purely because they have a clear preferred gameplan and a clear preferred 23.
If I was the Boks, with a Scotland win under my belt and a near guaranteed QF, I would be tempted to experiment in this match at 9-10-12-13-15 with a view to the Tonga match and the break to finalise their number one lineup in these roles for the QF. SA have shown they can almost throw any 15 together and be competitive, so it wouldn't be that they are giving up on the win.
Alternatively, they could stick with Faf, Libbok, DDA for Ireland (as the apparent current first choice) and experiment against Tonga but you aren't going to learn much in a match against such an inferior opponent.
The alternative seems to be mixing things up in the knockouts and I would not want to be doing that. They have brought Pollard in for a hooker for a reason, and that reason is not for him to be a third choice emergency fly half, so he needs serious game time in the pool stage where there is a safety net if things don't work out.
OR just resign yourself to Pollard being the sub in this tournament who comes on early if there goal kicking issues.
OR pick Pollard and DDA in the QF and abandon the more attacking tactics we have seen from the Boks over the past 12 months.
Personally I'd go Faf, Pollard, Willemse, AE, Le Roux for this match and stick Libbok on at 50 mins to not overwork Pollard. I'm pretty certain this won't happen but its a real headscratcher for the coaches.