I'd like to see the team take on the same big risk of 'quality content that some players may never even see' like they were so brave to do when they made Lurelin Village completely optional in terms of the Main Quest, and have a fair few unique boss enemies that are only found in one place in the world, and the satisfaction of fighting them is the main reward for reaching them over all else. What I WOULD like to see increased significantly with more uniqueness is big boss enemies. I'd be happy to see some more traditional Zelda enemies return, but they're probably best limited to particular biomes/dungeons so they don't get old or feel like padding.
Honestly if there's just two or three new common enemies and a few new weapon types or gimmicks (elements, armor, or magic buffs etc) that can be applied across the board to all 'intelligent' enemies, I'll be satisfied.