There should be a new mob that drops Iron Nuggets, and mobs carrying either Iron or Gold items should drop nuggets of their respective items on death. They should drop more nuggets the more gear they're carrying.
i like elytra but how about things like wings and jetpacks?
Mojang is hardcore about balance, and unlike most mods, they do include movement and logistics (e.g. item storage & transport) in balance. It took them until 1.9 before they introduced anything that would let a player fly -- then they made it a glider that wears out with use, and put that as a scarce prize in the new extension to the endgame. No way in the Nether are they putting in a jetpack or other generic flight. Especially anything that would allow lolflying (meaning "lol you can't reach me but I can hover and shoot at you").
Same for extended inventory or better storage -- note how the first "breakable chest" (shulker chest) is a rare drop in the same extended endgame.