Services to South Africa

So I read SAA are dropping Cape Town, one of the reasons being the cost of parking a plane at LHR for 15 hours each day!
Often wondered the economies of this, I think Qantas now leave 2 x 380's at LHR for a similar time, isn't there something cheaper to do with them?
Could we see VS making Cape Town an all seasons service? What happens in the summer to the LHR slot VS use for its winter Cape Town service.
Finally, I guess its MUCH cheaper to park a plane in South Africa for the day, than overseas airlines pay to park for the day at LHR.
Often wondered the economies of this, I think Qantas now leave 2 x 380's at LHR for a similar time, isn't there something cheaper to do with them?
Could we see VS making Cape Town an all seasons service? What happens in the summer to the LHR slot VS use for its winter Cape Town service.
Finally, I guess its MUCH cheaper to park a plane in South Africa for the day, than overseas airlines pay to park for the day at LHR.