I am still not sure why you need a timeskip to create said evergreen world.
Felwood is not less rooted because the things there happened in Reign of Chaos. Neither are the Plageulands.
Take my dream scenario of the new Westfall story concering a giant Legion dreadnaught crash landing near Moonbrook and being taken by Defias.
Yes, it would be tied to Legion, but you wouldnt need to know about the Legion-pre-patch to understand what is happening. The Burning Legion has attacked Azeroth, and this is a well-known fact, just because it is referencing a specific point in time doesnt mean it cannot be unrooted from things that happen afterwards.
Similarly I do no think any of the zones require a timeskip to make them timeless zones, they just need someone going in with the intention of making them timeless.
Botani escaped Draenor during the Mag'har campaign, you could easily create a timeless story set right after Shadowlands where they invade Feralas. Maybe the Ankoan or Jinyu are trying to settle around Vashj'ir, and that could be the story of that zone. Or Vulpera caravans travelling Kalimdor.
None of these stories require a timeskip, but they are nonetheless ungrounded from any overarching story if you want them to be.
Reatking Gilneas in gameplay terms consists of travelling there, possibly by ship, travelling back to Gilneas city and Genn making a speech.
It doesnt have to be fancy, but it is a large enough event it deserves its time to shine.
A year or two doesnt change much on its own, no. But if you add it up to all the previous years we have not spent in the relevant zones then you could easily add it up to a decade if you want.
As I said, there are very few zones that would "require" a timeskip to explain how things have changed, and pretty much all of those do not need to change.
Yes, it would be neat to have a New-Shattrath city on Azuremyst, but it isnt needed, you could just as easily have some basic houses and roads and I would be just as happy with the new Draenei capital. Same with the Nelves and Nordrassil.