The announcement trailer for The Legend of Zelda: Breath of the Wild's sequel was full of hints at the next game's story and gameplay. Much of the fan speculation regarded the possibility of a playable Zelda in Breath of the Wild 2. But if players can control Zelda in the sequel, it probably won't be alongside Link as a co-op partner.
Several aspects of the Breath of the Wild 2 reveal point to Zelda being playable, including her new, short haircut and Link's apparent corruption by the trailer's mysterious, green-glowing hand. Zelda's Breath of the Wild story arc and comments from Nintendo also suggest she could be playable in the sequel, but there's other evidence to the contrary. One likely Breath of the Wild 2 theory, for example, says the green hand could be giving Link new powers rather than hindering him in some way, leaving Zelda at a disadvantage when it comes to Hyrule-saving abilities.
Speaking to IGN, Zelda producer Eiji Aonuma wouldn't say whether Breath of the Wild 2 will have co-op. This vagueness has given some Zelda fans hope for the feature's inclusion, in spite of the aforementioned signs suggesting otherwise. But, from a practical standpoint, it's still not likely. Puzzles are one of the Zelda series' core elements, and co-op puzzles need to be designed specifically for two characters. Adding a second player to puzzles designed for just one can easily trivialize the challenge or prevent progression, negating the need for good timing or causing a player to become trapped. This is why some of the best 3D puzzle games, such as Valve's Portal 2, segment co-op puzzles to entirely separate modes.
That's not to say Nintendo hasn't successfully made co-op Zelda puzzles playable in single-player. The GameCube's Four Swords Adventures provided chaotic puzzles with friends that became more strategy-focused alone, as players could arrange their four Links into distinct formations to complete co-op objectives by themselves. Tri Force Heroes allowed for solo play, too, and dungeons in The Wind Waker forced players to coordinate with an NPC companion to solve puzzles. Most of these kinds of puzzles, however, function like Ocarina of Time's Inside Jabu Jabu's Belly dungeon, where players have to constantly babysit an NPC, protecting them from harm and dragging them around the area. This can be a fun bit of variety in moderation, but lugging around a helpless companion would get old quickly if repeated throughout a full-length 3D Zelda.
If Nintendo wants Breath of the Wild 2 to have co-op, it's stuck with a serious dilemma: It could design puzzles for co-op, allowing multiplayer in both the overworld and in dungeons but forcing solo players to somehow summon an AI companion when puzzles require it; or it could design puzzles for single-player, allowing co-op in the overworld but kicking player two out when dungeons roll around. The only alternative to this is designing entirely different dungeons for co-op and single-player versions of the game, but that's quite a big ask, and it would likely prevent drop-in/drop-out co-op. In all, adding a co-op partner for open-world exploration would make Breath of the Wild 2 a less lonely experience, but having access to two characters could significantly complicate puzzles and other problem solving-based game systems. Zelda could still be playable, but she'll probably be working alone.
The Legend of Zelda: Breath of the Wild was released for the Nintendo Switch and Wii U on March 3, 2017.