I'd say Star would have been talking with SA for quite some time. We know EK has knocked them back several times. SA is perhaps biding their time. I seem to recall an interview in Airways or some mag like that with some SAA honcho saying they weren't interested in alliances anytime soon and prefered to pick and choose. However this is the airline game so who knows?
I suspect CA (Air China) will be the next Star member... (although events in Mexico could get in the way)
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RichardMEL, UA 1K
A Star Alliance Member.