If they close down mainline and paint J* white with red tails then that would be a 'successor' and I reckon you're a fair chance of the IA applying. If they close down mainline and replace it with J* in silver then I reckon you could argue that's a successor too.
I don't think you could argue that it applies to the J* loco operations as they stand at the moment though as that's not a successor but a subsidiary and not Qantas Airways Ltd.