I think this is almost certainly accurate. That's probably about break even on the disk version, and a small loss on the diskless. But, the diskless is better for them in the long run, so a subsidy on the front end makes sense. This also allows them to push people toward digital without the bad PR that would come along with forcing it on everyone.
The fact they delay games because of the physical copies show how important physical copies are.
Pocky Lover Boy!