After getting a sharp rapping on the knuckles for the on-disc downloadable content in Street Fighter X Tekken, Capcom promised it would be "re-evaluating" its policy. The company must still be thinking it through, because the company has cited technical reasons to necessitate a piece of on-disc DLC in Resident Evil 6.
A modder on YouTube found hints of upcoming content, most of which is only referenced on the disc. References to more map packs, 4-player game modes, and co-op for the Ada campaign weren't accessible from the disc, meaning that those modes aren't built into the game and will actually be proper downloads. But a "No Hope" difficulty mode is accessible through modding.
In response, CVG reports that Capcom has confirmed the presence of the DLC, and explained the decision. "We still have unannounced DLC for RE6 that will be revealed in the coming months," the statement reads, "and while virtually all such content will not be on the disc there will be one piece of content, that for technical reasons, requires the use of a combination of newly downloaded data and data that is included on the retail game disc."
It does make some sense that the difficulty mode would have to be built into the game from the start, and to be totally fair we aren't even sure if Capcom plans to charge for it. The "newly downloaded data" would probably serve as an unlock key when that time comes, so we'll have to wait and see where Capcom prices it.