If the premium economy is no difference or very little... like say China Southern's premium economy then yes i would not want to pay much at all extra for it. But we'll have to see on this. Its all guessing. Though like you i am inclined to think they may do the same.

But then the product will then need to priced correctly.
By the way the business class will increase in price after these upgrades? As they wont have the 60+ seating they have now on their 747's if including first.