These are all great ideas, and I hope some of them are implemented in Zelda U, but most of them don't really reach the same level of relevance as the wall merging mechanic in LBW. Wall merging is a primary mechanic that informs the level design of every screen in the game. It's basically of the same relevance as jumping is in Mario. And it's as seamlessly integrated too.
Well, you're right that they aren't singular mechanics that change the way the game is designed/played, but they do contribute greatly to the sense of "player freedom" that Aonuma often talks about. And ultimately "player freedom" in a broad sense is a concept-level vision that informs the design and gameplay.
But, yeah, I'm probably placing too much importance on my fanboy ideas. ;p
I don't think we're going to get something with that level of relevance in a huge, highly detailed, organically structured 3D game (as compared to a smaller, lower detailed, inorganically structured 2D game).
Yeah, me neither. I don't think it's an appropriate way to think about game design in a 3D world.
However, this:
could definitely come close to reaching that level of relevance. If done correctly, this idea could really shake up both the zelda formula, and the open world formula.
Right. In a sense it'd almost seem like a retreat from the typical assumption that Link just constantly gets more tools that are always at his fingertips, and thus can conquer whatever he's up against with ease if you know what items to use. But it'd enable [modern] Zelda to transcend the boundaries of its genre (for example, becoming more RPG-like) without abandoning its core values (like action-based combat that uses simple, intuitive controls) in favor of "hardcore" game mechanics (i.e. without implementing a heavily numbers-based stats system).
It'd also redefine the way enemy encounters are handled, without completely crushing the controls longtime players are used to. You simply choose the weapon scheme you think is more appropriate for the area you're checking out, or the one that matches your personal playstyle - not unlike Splatoon. Maybe you're up against armored foes, so you bring a sword and shield so you can weather heavy attacks. If you're up against ranged foes, you bring a bow, but you have to leave the shield behind, which leaves you more vulnerable but lets you strike from a distance.
This skews the combat away from the "super powerful main character that has tools on hand that can wreck everything" to thoughtful combat where you have to either choose the equipment that's best against the enemies you're up against so you aren't outmatched, or become skilled enough with whatever you like to use to take them out despite being at a disadvantage.
At the same time, elevating combat and equipment in this way makes them both massive complements to exploration in more than just the "lock and key" fashion we're used to from past games. For example, if you don't always have the bow handy, you might need to improvise to solve certain puzzles, or pay extra attention to hazards and enemies that can attack you from a distance. But if you have the bow, you might need to be more careful to stock potions since you won't be able to deal with crowds of enemies with the same efficiency as you would with your sword.
All of this will also complement the "easy to play, difficult to master" mantra that made Nintendo games really memorable back in the day. If you play through the dungeons in the "proper" order, and use the "proper" equipment, you'll probably not have a very tough time. But with the open-world approach, you can break the order as much as you want, and on top of that choose equipment that's less suited against particular enemies or bosses for an extra challenge.
When I thought of using Epona as the "storage" for your items, the place you can go to change out equipment to suit the situation, I was really thinking of two things:
1) Limiting equipment
Traditionally, Zelda games let you carry every single item you get over the course of the game simultaneously. This often results in Link being super overpowered at the end of the game, since you can switch to whatever item works best for a given situation at literally any time. It also leads to some lazy enemy design, where certain items are "keys" that easily defeat the enemy, and the game can safely rely on this kind of design because of course if you're at that point in the game you probably have the right item.
What if you're limited in the number of items you can have equipped at once? This would shake up the role of items, where the ones you choose are more about giving you certain advantages or disadvantages instead of having the "key" you need to solve a certain "puzzle" (including both environmental puzzles and combat ones).
Any enemy can technically be defeated by any [primary] weapon, and you won't need to bring along any particular weapon to solve puzzles - so being locked in to a certain weapon won't prevent you from progressing if you don't have the "right" one. Instead, it'd just be
easier or
harder to solve certain puzzles depending on which weapon you bring. This would offer tremendous flexibility both in terms of how players approach dungeons and how they approach enemies.
Unfortunately, most RPGs implement these "limiting" elements through annoying mechanics like equip load (which forces you to drop excess items off at a particular location, thus "limiting" the items you can carry), or by locking you into a particular "class" (that can only access certain kinds of equipment). I don't think either of those would be a very "Zelda-like" approach; in fact, it's a real pain in the ass that drags down exploration and discourages me from looking for items.
Hence:
2) Without crippling convenience
Instead of having a hard "equip load" system or a "class" system, what if a Zelda game used Epona as a means of switching out equipment? You can call Epona at any time from anywhere in the field, and she'll be there in a couple seconds. No need to fast-travel somewhere to switch out items, then make the trudge back to where you were. This would enable the team to include a wide array of weapons, enforcing the limits I described above without making it cumbersome to manage all your items.
To keep the "easy access" from interfering with the limitations of the equip system and the overall balance of the dungeons, perhaps Epona can't follow you in dungeons, so if you want to enter a dungeon, you'd better go prepared or hope your sheer skill can overcome the obstacles within. And if you pick up extra items while in dungeons, but don't have access to Epona, you won't become overburdened - you'll just have to keep them in your pouch until you return to your horse.
Another bonus of the "limiting" approach to items: could be a foundation for satisfying co-op, kind of like Nintendo Land's "Battle Quest" but implemented in a full Zelda game.