Yeah, 11 numbers does seem like a lot... But, the caboose is road and era specific, so you're hoping that the number of Z scale SP modelers, plus certain collectors who need one of everything, results in 144 sales. That seems a bit hopeful as well, even if Z is growing.
These hoppers are era specific also, but ended up everywhere, so the pool in this case is Modern modelers in Z. More sales, but I still can't picture 11 numbers at 60+ cars produced in each number.
The project was chosen because the Canadian hoppers are the number one selling product in their HO and N lines. I just hope they scale the production appropriately for Z. If they end up with tons on the shelf, are they going to be gun shy on the next release? Expectations need to meet potential demand.