A359 fits in between the 787 family and 777X. AC's 777s are not due for replacement and 787s are in ACs sweet-spot for range seats and cargo. When it comes to replacing the 773s the 777X's beat the A359 in terms of seats and most especially cargo capacity and have the benefit of similar type rating to current 777s.

I don't see any logical reason for AC to purchase A359s.