I really don't know what to say...
This case is really tricky... About YVR to HKG, I am not that much worried about it -- I am sure that either Boeing 747 or an Airbus A340-600 will do the summer runs (at least, this year A346 runs on the HKG-YVR route till the end of September). But HKG to JNB -- that is a tricky situation. One thing for sure is that they will not put on on SAA flight (even SAA runs some A340-300 subs on this flight)... Also JNB does not seem to have that premium traffic load -- SQ has converted the JNB routes with all two class Boeing 777ERs. So it is hard to spectulate...
Maybe you want to postpone the trip till November, when the high season is here and the JNB flights will most likely be run by the larger Boeing 747s...
For now, you can check on it daily... , but new schedule will not likely come out till Jan next year...
Carfield
PS. Also it depends if CX will confirm the leasing of BA's 15 (or 14) Boeing 747-400s, the delivery schedule, and how many of them will be used for pax, and how many will be used for cargo?