Unused capacity
I think a lot of installed HDD capacity is going unused, especially in domestic PCs and that will tend to increase as areal densities increase. Manufacturers of PCs know that if they have a choice of fitting a 1TB HDD or a 500GB SSD at the same price, the 2x price premium of SSDs is not sufficient to choose a HDD.
HDD manufacturers could offer crippled drives at a lower price, but that won't change the manufacturing cost. One option might be to shift to making a lot of drives smaller than 2.5" .
Biting the hand that feeds IT
