When Demise was defeated in the past he was still in the process of being revived/released (hence why he wasn't at full power)... but that process had not been completed (if it had then Zelda would have lost her soul), so it's not much of a stretch to assume that a part of him was still sealed...
I don't think Eldin Volcano was renamed Death Mountain... I think Eldin Volcano fell dormant/extinct, icing over and being renamed Snowpeak and later the Hebra Mountains... and this climate change is what likely killed the Mogma (or at least caused them to leave Hyrule).
The name Death Mountain...
Demise's curse and the spirit of the Hero are intangible things that cannot be destroyed... but the bloodline of the Goddess is not... it can be destroyed... and as the Zelda name is passed down along the bloodline, then that (and the Legend of Zelda with it) will end when the bloodline is...
The way I rationalise it is that while every game does have it's own downfall timeline (potentially multiple ones depending on when or how Link dies), in those timelines the Legend of Zelda comes to an end... no more Links and/or Zeldas can be born, so there's no more story to tell... hence no...
There's one detail you seem to have overlooked... the location of the Triforce.
When Link gets sent back to the past in OoT the Triforce is split between Link, Ganondorf and presumably Zelda... yet the TP backstory shows the Triforce as being in the Sacred Realm when the Interlopers attempted to...
Leviathans don't necessarily need to be sea creatures... they can be any sort of creature that is particularly large, which makes sense considering how different each of the skeletons in BotW are from one another.
Personally, I'd be more tempted to compare the leviathans to dinosaurs more than...
I think it was good, but could have benefitted from some late-game upgrades.
Early in the game the rain was an interesting obstacle, but later in the game it could become frustrating (especially when you're half way up a tall cliff when it starts)... so maybe some gear to allow you to climb in...
Seeing as you can choose between heart containers and stamina vessels, and can do most things in the game in any order, the 'progress at this point' will vary from player to player, so I think that's probably just an aspect that's been carried over from past walkthroughs that is now somewhat...
The Gerudo had basically shut themselves off from the outside world, only venturing out to steal or find a husband... even when Ganondorf took over Hyrule the vast majority of them kept themselves shut away in the Gerudo's Fortress... their behaviour is defensive, not offensive... so it seems...
I doubt he thought they would go to war... there's no mention of the Gerudo having been involved in the civil war that took place prior to OoT, and there's no evidence of ill will between the two races that implies they had ever been at war before... the Gerudo were just reclusive thieves...
Prophecies are typically depicted as being rather vague, requiring some degree of interpretation to determine their true meaning.
The same appears to be true of Zelda's prophetic dreams... in them she only saw dark clouds that represented the evil threatening Hyrule... she interpreted that as...
Melee - Pikachu (or Pichu if my friends refused to let me be Pikachu)
Brawl - Pikachu (or occasionally Metaknight if we were weren't playing seriously)
4 WiiU/3DS - Pikachu (sometimes Greninja... but we tend to do random most of the time now though)
Although me and my friends are fairly evenly...