I think having more varied dungeons would be nice for the next game. I wouldn’t say 12-15 like Shadow1989 said, especially, if we go back to the open world concepts of BoTW. That would be an incredible undertaking. If we’re talking a smaller world, then maybe close to 10 would suffice.
With weapons, it depends. I can see why they left the hook shot out. It would’ve been a bit too easy going around in dungeons and shrines and a bit too crazy in the open world.
I would like to see more side characters get some limelight. While Riju, Saidon, Kass, Purah, and the Champions were great, they were notably underdeveloped. Though I was actually quite surprised by the development of the King and Princess Zelda, who remains the best version out of all the Zeldas, to me.
Other than that, I think they have options to go for post-BoTW. While BoTW remains an incredible experience, it’s also a great concept to continue building around. However, I can also see them take a Majoras Mask-like path and go unconventional, though it’s funny since they already went unconventional with BoTW.
As for music...it depends on the path they choose. I personally think the music and ambiance were great for BoTW because they fit with what the developers were going for. I don’t think an overworld number akin to OoT and WW would’ve worked well with BoTW as it might’ve overstated it’s welcome, especially when the next stable is farther away compared to the long distance between islands in WW. I even appreciate the behind the scenes footage of the music and sound effects they produced. I really encourage people to watch those behind the scenes videos if they haven’t so already.