Personally I would love CPT as a destination. I spend a lot of time in South Africa and don’t love connecting through Europe to get there - sometimes with very long layovers as many TATL flights arrive in the morning and many flights from Europe to SA leave in the evening.
But, on the other hand, is it good for business? I suspect there is very little business traffic. It looks like the two countries have around $2B of trade annually, mostly precious metals. On one hand, the precious metals could be shipped by air and earn good revenue (presuming they don’t get stolen at YYZ). But it wouldn’t be very diversified, and there’s a big trade deficit so the traffic would be very one-sided.
So then AC would probably need to rely very heavily on tourist traffic. I guess it would probably only do a seasonal flight, so a higher likelihood of available aircraft during the Canada winter months. But again probably very one-sided traffic: mostly Canadians going on holiday to Cape Town.
It’s hard to see a world where the economics would work out.