I would love to have Operation Javier DLC, but that would have to be built from the ground up. I don't see it happening.
Capcom usually recycles assets. Sure, the mines in RE7 were kind of new. At least some areas were. But I don't think they would have taken an awfully long time to develop. With the mission with Leon and Krauser being in South America though, they'd have to design entirely new levels such as the jungle and the dam, and Javier's mansion.
So I don't think DLC is coming. Separate Ways may still be coming, though.