Dungeons- I think the next game needs dungeons. However, I am not calling for Wind, Forest, Fire etc., type dungeons you'd find in most games past OoT. What I'm thinking of is old ancient and spooky ruins that lie underground, that are falling apart and that contain buried history. Old tombs, old underground cities that are connected by dusty dark tunnels, and hidden treasures.
This sounds like an awesome idea, but having a few elemental dungeons to go along with them would be great, too.
Story- I think they need to continue to expand on Ganon to keep him interesting. He's gone from Big Blue Pig to Gerudo King/ King of Thieves to Ganondorf to Demise's Curse/Hatred Incarnate to Calamity. What is he going to be after this? My favorite idea is that he's revealed to be a super powerful demon (Ganon) that long ago possessed a male Gerudo baby. Two reasons why I have this as my favorite idea is that it comes back full circle to what Ganon originally was when we first saw him in Zelda 1, a demon pig. Second is that many people are fans of Ganondorf's 'sympathetic' portrayal in WW, so in a way, him being 'possessed' means that the human (Ganondorf) is sorta off the hook.
This on the other hand...
1. Ganondorf and Ganon have been confirmed to be one in the same person since ALttP, and in many games since.
1A. The name Ganondorf was used in the manual of ALttP, which also confirmed that Ganon was a common name before he transformed into a beast. In the final battle, Ganon disparagingly calls Link ''boy'' and ''lad''; In OoT and TWW, he also uses terms similar to that and ''boy'' in OoT and TWW in the same manner.
1B. Ganondorf transforms into Ganon at the end of OoT. Also, his castle is called Ganon's Castle, before he transforms into a demon.
1C. In TWW, He's constantly referred to as just ''Ganon'' by the KoRL for a vast majority of the game, despite never even transforming into his demon form in TWW.
1D. Zant calls him Ganon and Possessed Zelda's title refers to her as ''Ganon's Puppet'', before he turns into his demon form in that game.
2.No evidence of Ganon(dorf) being possessed by a demon in any game.
3.Seperating them like this makes Ganon(dorf) a pointless character:
3A. The weight of Ganondorf's actions in OoT, such as destroying the Market, feeding the Gorons to Volvagia, and just putting Hyrule through hell for seven years is nonexistent, because it wasn't really him, just some demon that is offscreen and barely even alluded to until the final battle(although it looks like Ganondorf willingly uses the ToP to transform into him, you know, almost like they're the same character). Although that would leave us with the question as to why Ganondorf is sealed away if he was innocent?
3B. Why should I care about DT Ganon? If we separate him from Ganondorf(despite the fact that doing so contradicts the story of Ganondorf as presented in the games), then he's just some mindless idiot who wants to destroy things, making him boring. But, if we take him as being the same being as the man once known as Ganondorf, (as the games present him as), then we have a tale of a man who desired power, and upon getting it, had his humanity ripped away from him, perhaps eventually resulting in him becoming the being known as the Great Calamity(if you place BotW on the DT as I do), meaning that Ganon loses even if he wins in the short term, making you almost feel pity for him despite his atrocities over the millennia.