My hope is that Avaloren is this massive continent where WoW can have a proper reset after the WSS.
When TWW comes out, when you start a new character your levelling progression is like this:
Exile's Reach: LVL 1-10
Dragon Isles: LVL 10-70
Khaz Algar: LVL 70-80
After that, with Midnight you should reach 90, and with TLT you should reach 100. I think it would be better for the game if they kept the progression like this until the end of the WSS. That would mean they'd have to keep the Dragon Isles as the first place you go to after the first 10 levels. DF sort of acts like a prologue to the WSS anyway so I don't think this is a bad idea.
If they decide to replace the Dragon Isles with Khaz Algar as the first place characters go to after Midnight releases I think that will hurt the narrative they are trying to build. Even more so if they replace Khaz Algar with the Midnight zones after TLT comes out.
After the WSS they can use Avaloren to "reset" the game. Squish the levels back to 60 (ideally I wouldn't want that because I like seeing number go up) because having it go above 100 again might be daunting to some players, especially new ones.
Avaloren could be so big that every race can have it's own little starting zone/outpost. The Holy Empire of Arathor doesn't have to span the entire continent. The Zandalari and Kul Tirans each had a small island and even they had issues there, it shouldn't be out of the question that a massive landmass like that is diverse with different cultures that have opposite ideals and especially different biomes.
I think this is better than having a messy narrative like we do now. You don't really know what's even happening when you are levelling. One of the things I dislike so much in ESO and why I didn't keep playing that game is because nothing makes sense, and it legit feels like you need to consult a guide to know where to go chronologically to understand anything. Guild Wars 2's narrative is way better, and FFXIV's is the best example, although the latter can be quite extreme and limiting for people that don't care about that stuff.