Over twenty years there has been a ton of mats from vanilla to The War Within; each unique to that expansion.
What if, instead of generating a new template of mats for new zones, you instead use the myriad of mats from existing expansions to create expansion-relevant gear using all the craftable plans, designs, etc. from twenty years’ worth of development?
You can assign certain mats from an expansion to express a particular stat, or combine stats to create even stronger gear.
For example, you have a Frost Tiger Blade recipe from Vanilla that you want to imbue with more Frost Damage, Mastery, and Crit.
So, you would have your initial mats for the blade, then you could add in the reagents for ilvl (for the current expansion, and additional reagents like Frost Orbs from Wrath to give you more Frost Damage, Imbued Frostweave Bolts and Cobalt Ore for mastery, and cosmic essence for additional crit+mastery.