I don't think they'd pull a 747 going international for one going domestic. I'm guessing that the fares for the international routes are going to result in more money versus the HNL-ATL run, and thus it would make more sense to keep the plane going to KIX or NRT. One night when the HNL-MSP nonstop (on the A330) was canceled, a GA told me it was because the A330 going to NRT or KIX had broken, and so they pulled the domestic run. There's also the cost of messing up internationally (not that that necessarily means a lot to DL). Last, it's a lot easier to route a bunch of pax that were on a canceled HNL-ATL flight than a canceled HNL-NRT/KIX flight, since so many more flights go to the mainland from HI.

Point being, I don't think it's valid to think that a international-bound 747 would be used to fill in for a domestic 747 (in most cases).