Interesting points about the Polar routes on the 747-8F.
Perhaps it comes down to lease or small order of 748Is vs more 77Ws before the 77Xs start coming. If the lift is needed (and I'm not saying it is), I think CX will try to determine if they can make more money (ROI) from the 77W or the 748I. I think the A380 is essentially out of the running for a litany of reasons, but the same might be true of the Intercontinental as well.
The true economics of the -8 improvements and the price of the aircraft relative to more 77Ws will probably be the deciding factors.