Considering how lazy the DLC for BOTW was wouldn't be terribly hopeful they'd do much in terms of new areas. This really does sound like the sort of thing other companies would do as a DLC pack.
Yes, because the mindset and mentality behind developing DLC expansion packs is totally the same as that of developing a brand new game.
Hardware Comparison Threads:
PlayStation 4/Xbox One/Nintendo Switch: 2019 vs. 2020