I do not believe SA will be the 5th continent due to simple logistics. Going to SA pretty much adds one or two days of flight itinerary, and this race seems to be lagging behind its predecessors in number of legs finished (we're already 2 weeks in, so teams should probably be on the 8th or 9th leg in Africa right now).
Also, based on past India double legs, Kolkatta should be the only Indian city visited (they didn't take a train elsewhere). That leaves open the possibility of a double leg there, though. Lastly, I believe India is the final Asian destination before Africa, and that there will be 2 legs in only one African country north of the equator to speed up production (why do I suspect Egypt?).
In summary: a double leg in Australia, 4 legs in Asia (5 if Laos is visited or there are 2 legs in Kolkatta), 2 legs in Africa, and 3 (or 2) legs in Europe. Of course, if the race lasts longer than 3 weeks, then everything I said just goes out the window.