darkSpyro

1. SFX/dialogue/UI asset extraction (in addition to the music one you listed)
   
2. Flame/Ember/TLOS characters/etc playable (I figure this might go under model mods)
   
3. Heck maybe a whole TLOS overhaul to the game
   
4. Spyro: Survival Mode
   
5. Online multiplayer -- maybe add a chatroom feature like Spyro's Lair
   
6. Golf minigame -- let's face it, Spyro's done just about everything besides golf
   
7. In-game character customization
   
8. Boss gauntlet
   
9. Pokemon playable in-game (sort of like that mod in Minecraft that lets you play OG Pokemon)
   
10. Overhaul game into a fighting game (like Smash Bros or Streetfighter; that sort of genre)
    

Your list is... I think everything I want. I was mentally making a list to prepare of my own but you may have covered it all
I do know
If the community achieves the retro graphics with the low poly models being accurate, environmental modifications and texture+ vertex shading...
My hope is those fan game projects will transfer over into Reignited
But my fear, and I will understand, is first
That itself is a large task
But not only that, will the original creators be willing to re do everything they had done? Or will they be burnt out and have already given up?
I can dream that that won't be the case...
Because still... the hush-hush game was everything in a fan game to me... ; ~ ;


Edit: I just did think of something that would be a neat mod:

Japanese Spyro Mod- configurable camera mode in the menu that you can toggle to that isometric angle, or regular camera, i.e defualt. Spyro's model is styled after the Japanese boxart, has the OG Japanese voice clips, and most importantly, all the dragonfly eggs are added into Spyro 1 and 2, but new ones are introduced in 3, alongside and upgradeable and customizable Sparx.

Oh, man, if they could get 60 FPS I might actually decide to install Steam and buy the game again. <.<

A mod to change the music in the levels would be amazing, just think about what kind of mood you're setting if an emotional piece in a Final Fantasy game was playing while you're charging at enemies for mooning.

Worth nothing that Reignited Trilogy likely won't need dedicated tools to do things like level mods - it's built in Unreal Engine 4 which is already publicly available for anyone to download. What does need to be done is for the game's assets, actors, etc, to be reverse engineered so that they can be opened in UE4, and then exported from UE4 back into the game. Once that's figured out, you can just use general UE4 knowledge for things like building level geometry and placing the reverse engineered actors.