I wouldn't put it past KT to do DLC---and to be honest I think I'd like them to wait a bit for a sequel so they have more games to draw from. But we have SS which sort of got left out of DLC, and then Triforce Heroes and BOTW so...my DLC wishlist!
Free DLC: Groose.
The Groose is loose! His weapon is the Fire Elemental "Bomb Bag", and he's also equipped with Digging Mitts. I envision Groose as basically a jock, so he'd show off and basically kick and toss bombs around like various sports---like his WPS on a regular foe would be doing an Inazuma Eleven-style kick, and his WPS on bosses would have Mogma pop out and throw him in the air as he spikes a bomb at the boss. And of course his Special is the Groosenator. I'm thinking his Strong Attack would be he could bury up to three bombs underground, which would explode when an enemy steps on them OR when he finishes a combo string they'd all explode.
DLC Pack #1: Skyward Sword Pack
* New Character: Gaepora. His weapon is the Light Elemental "Book", which allows him to summon ancient Hylian symbols to attack, as well as transform into a golden owl---by holding down the Strong Attack he can study, filling up a bar. When the bar is full pressing the Strong Attack again allows him to transform into an owl, and he can warp to any captured keep as if he was an Owl Statue.
* New Weapon: The Electric Elemental "Timeshift Scepter" for Impa, since it's implied to be Sheikah technology. Using this weapon allows her to reverse time and summon various mechanical lifeforms from the Lanayru Province of SS such as Beamos. Using the Strong Attack she can leave herself vulnerable as she becomes the old Sheik from SS, charging up her Magic and Special very slowly. Her Special could have her reviving that lightning dragon from SS, and maybe her WPS have the robot pirate appear.
* New Adventure Map: Skyward Sword!
The bottom of the map is the Ground, and the top of the map is the Sky. To transport between each, you need to battle on a square marked with a Loftwing (to move up) or a Sailcloth (to move down). On the ground are Goddess Cubes, which appear within the map in a keep and by freeing the keep and keeping it safe till the end of the battle you'll unlock a corresponding treasure above. Items include Scrapper, who can retrieve unique Item Cards from the Ground which you must take to a certain area in the Sky, Mogma Mitts, which can be used on holes, Gust Bellows, which can blow away gust, Whip, which can pull levers, and Time Stones, which are used to reveal enemies. Find all three Ancient Tablets!
Groose's upgraded weapons, as well as Gaepora + weapons and Impa's new weapons are available here!
Also various outfits based on SS---forgive me if these have been done
- School Uniform Link, Zelda, and an original one for Lana and Marin.
- SS Impa
- Zant that makes him resemble Scrapper's color scheme?
- Dodoh outfit for Tingle
- Faron and Eldin-style outfits for Ruto and Darunia.
- Koloktos armor for Toon Zelda's Soldier
- Scervo-based outfit for Tetra.
DLC Pack #2: Triforce Heroes Pack
* New Weapon: The Darkness Elemental "Pom-Poms" for Toon Link, which allows him to summon two Link to aid him like in Triforce Heroes---as well as some references from Four Swords thrown in as well, though with only three Link. It's "Darkness" because the Links act very over-the-top and pose and such, which just confuses the enemies.
* New Adventure Map: Hytopia
The "final" Adventure Map, this map is designed to help you with the other Adventure Maps as rupees and materials are given out a-plenty through the varied challenges! The challenges are very varied, such as limiting you to a team of three certain characters, making you use all the same elemental weapons, a "girls only" battle, and stuff like that---also characters are randomly given different outfits available to them to spice things up! There are only three unlockable items on the map itself, and no Item Cards---the Pom-Poms and their upgrades. Every time you complete a mission you gain "Hero Points", but only on the first time you get each rank---C is 1, B is 2, and A is 3. But they don't add up---so if you get C, and then get A, you'll get 2 in total.
At the Madame Couture space you can use Hero Points to buy various costumes, there is one for almost every character (except Groose and Gaepora since they're optional DLC, and the next DLC set) at least drawing from the outfits from Triforce Heroes, or their characters, plus some bonus stuff like the BS Legend of Zelda baseball cap for Link and Zelda. Basically, an Adventure Map dedicated to costumes---which are a big draw of Musou's imo.
Final Expansion Pack Breath of the Wild
* New Character: Urbosa. Wields the Electric "Daybreak Shield", but this also comes with the Scimitar. Can use lighting attacks, and also call forth those sand seals and surf on her shield. When finishing certain combos she leaves electrical orbs on the field, and when using her Strong Attack they cause them to erupt into electrical explosions.
* New Character: Kass. Wields the Water "Accordion", I haven't really thought much about how he'd play but---c'mon, he'd be cool to see. I'm thinking possibly utilizing the other three Champions' powers in some way, maybe giving him support skills that aid the morale of his team to mix things up?
* New Weapon: The Light Elemental "Sheikah Slate" for Link, which can use the various powers such as freeze, stasis, and magnetism. Also as you collect materials a bar fills up, allowing you to ride on the Master Cycle which goes super fast and plows through enemies.
* New Weapon: The Fire Elemental "Frying Pan" for Zelda. Based on the cooking mechanic, and also referencing the broken weapon mechanic as it will sometimes shatter (but she'll just pull out another one!), every combo string gives you a certain ingredient under your life bar. Using Strong will mix these together, and the resulting food based on the ingredients will give you a special boost temporarily in a various area.
* New Playable Stage: A completely new stage based on Breath of the Wild, mixing all the key areas in and with the giant robots (I so forgot a lot of terminology!) in the background. Also introduces some new variants of enemies based on their appearance in BOTW, as well as new mini-boss enemies in Guardians, who are very powerful. When playing on this map you can find Ancient Arrow upgrades which allow you to hit their weakpoint, much like Gohma.
* New Adventure Map: The Wildlands
This adventure map is completely separate from the rest---every character is reset to level 1 and don't have access to their regular items, instead you have to level up separately in this map and use the weapons you find. Every character can obtain up to Level 3 of any of their weapons though but they aren't carried out of this mode. However, like in BOTW, each weapon will break after one use so save the best one you can for when you need it. You obtain rupees, but you cannot spend them in this mode---there's no Fighting Dojo available nor Smithy. The only thing that carries over in terms of character progress is Materials and Badges.
The goal is to journey to each of the four Divine Beasts, with each one giving you a different unlock---camel is Urbosa, bird is Kass, gecko is Frying Pan, and Elephant is Sheikah Slate. The upgraded weapons and costumes are spread out on other parts of the map, but certain rewards are unlocked till you beat the Divine Beast square---like say lava is block one item because of the gecko, or the water is too high because of the elephant. There are no Item Cards thus. There are guardians which move around on the map, and stay on spaces---if they're active on that space, they'll appear in the mission to bother you, but if you win they'll be gone for awhile. There's also the Blood Moon which occurs on occasion that resets the guardians and makes the enemies in each level much tougher, but results in better rewards.