We're apparently going BACK to Khaz Algar in 12.1.7, and all this back/forth makes me think that the story was meant to have all these places more closely connected in space/time. I drew this up while talking to my friend about it.
Harandar should have been physically connected to SOMETHING on the map without being a portal. Putting it under ZA and Eversong like Hallowfall would've been a cool parallel to the WW map.
Have both "continents" connect through the Ringing Deeps. It's almost like BfA but no faction war, just Horde working with Horde characters and Alliance working with Alliance characters. Earthen are an Alliance-only Allied Race. Haranir are Horde-only (for now).
Start with Twilight Cult, no blueberry voidwalker army, in both regions. Twilight's Blade or the dark Beledar cult are the instigators. First patch we fight them off and only at the end of the patch do we learn that Xal'atath leads them. The Zul'jan/Zul'jarra story happens in ZA and Zul'jan opens the Coiled Isle. It's not a whole zone, just a raid portal at the entrance to Atal'Utek.
Do the Ula'tek raid -first- in this whole saga, so that Kith'ix can use the Nerubians instead of random Aqir to attack Dorn and Quel'thalas from Azj-Kahet. Kith'ix as the endboss of Nerub'ar Palace lets him and the nerubians feel more epic/drawn-out and maybe not as wasted.
Kith'ix is the character who gets "absorbed" by Xal'atath to power the Voidspire. That way Dimensius can also be used later in the story when it wouldn't be out of nowhere.
Then Voidspire/L'ura raid is the third/fourth raid of the saga and then the 5th chapter is the Worldcore.
Instead of 3 micro-expansions, this whole story could've been better serviced by being one mega-expansion told across both regions at once.
You still have Alliance characters going to Silvermoon for the March on Quel'danas, you still have Horde characters going to Dorn where the story calls for it, but they start out in places that have more cultural context and make more sense where they'd be in the story.
No Undermine or K'aresh either. You'd have to streamline it all to not bloat the whole thing and have too much work for the devs.