I know Nintendo rarely makes remakes of ancient games, but hear me out. Since thise two games are the oldest and most bare bones entries due to console limitations, they have the most potential to expand. Not to mention tweak and update. Say goodbye to the "Lives" and other oddities that made the originals a pain in the neck to play.
I'm thinking something similar to BOTW, but not exactly the same. Just as Ocarina of Time and Twilight Princess are similar but different. Since Both games are focused on mostly open world exploring. The Great Plateau from BOTW is bigger than OOT's overworld. Meaning that the Original Legend of Zelda could act as this game's equivalent of the Great Plateau. Once you beat "the tutorial" you get the time skip, just like OOT. With Older Link we lose access to certain weapons, but gain access to others. Things like breakability, reliance on the MAGIC meter, requiring a cooldown (like the Master Sword) could reduce the abusing of certain weapons or spells.
The world would get an overhaul and feel more organic and not have everything forced to a grid. Dungeons and palaces would be where the bigger changes lie since adding the third dimension can make sense of the nonsensically long hallways and townsfrom the 2d era.
Then we have the storyline. Without the 8-bit limitations, the story can be fleshed out and make some things less videogame cryptic while keeping the cryptic atmosphere. Speaking if storyline, the dosconnect between The Original Legend of Zelda and Zelda II: Adventure of Link can be fixed. In BOTW, the Great Plateau acts like a Zelda 1 map within the Zelda 2 map. Storywise we can claim that the Zelda 1 map is a magical recreation of different environments from Hyrule, maintained by the remaining members of the Sheikah to train potential champions/heroes. These training grounds were built at the base of Death Mountain due to the inhospitable area surrounding the grounds, which would avoid normal travelers accidentally entering the training grounds. Not only that, but with being able to expand the storytelling abilities, we can get more lore. The ability to make the original games be more connected to the 30+ years of lore that came after... We can even explain better the 2 Zeldas. We have the Zelda that we rescue in LoZ and hand over the Triforces of Power and Wisdom to her and we have the Comatose Zelda hidden within the castle...