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.
I doubt there will be a $100 difference just because it has a disc drive. If anything, I could see them pricing the digital version for $399, just so they hit that price point again, while pricing the physical version at $449.