SAA has been talking about starting services to Beijing and Japan. The A345's could be just the ticket for this. They may well also be used to boost frequencies to the US, offering a non-stop westbound routing.
A345 two class config of 42+225 compares with SAA's config of 48+291 on their A346's. Perhaps AC
is keen on leasing/sub-leasing their aircraft to SAA as an interim measure for a while?
In a recent newspaper article, the SAA CEO stated that SAA is considering a follow up order of up to 9 additional Airbus aircarft (4x A380, 5x A345/A346)