A theory about those 128 GB in those new iPads

This may be far fetched - judge for yourself.

A typical Apple strategy is to buy as much of a resource as possible, for economies of scale and to cause problems for their competitors. They have done so in the past with SSDs, so I think Apple still has contracts in place to order as much SSDs as feasible.

---->Apple has lots of SSDs that they either sell or store somewhere

---->Apple sold not nearly as many MacBooks as the quarters before, maybe not as much as they had planned. MacBooks use a lot of SSD space

---->What do with the SSDs? Build them into the product that does sell well -> the iPad.

I'm not saying it's even likely that it went down that way, but I found it an interesting theory. I have no idea how contracts like SSD purchases are beeing made in the industry, but figured the contracts may have been too long-term for Apple to quickly react on less Mac purchases.
What do you think?