So, this may be a completely crackpot theory here, but I want to throw this out: What if the waking of Mordremoth has something to do with Abaddon/Margonite and could possibly bring back into view White Mantle/Mursaat.
I typically ramble, so I’ll just put what I see.
As we move farther into Maguuma Wastes we draw nearer to the Bloodstone in Bloodstone Fen where in Guild Wars 1 we found the White Mantle sacrificing Shining Blade. Silverwastes is the closest we’ve been to it basing it off Dry Top which correlates to the location of Dry Top in Guild Wars 1 (if I’m correct we should be around Aurora Glade leading into Silverwood/Quarrel Falls).
The tendrils/roots we’ve seen from Mordremoth have resembled those that we saw from Abaddon in the realm of torment and they even have the same purple glow that the Margonite had (based off the vines in Silverwastes).
Now, the Bloodstone was broken apart because the magic was too powerful and caused chaos and war amongst the humans of Tyria. It was broken into the four schools of magic Preservation, Aggression, Denial, and Destruction with the fifth uniting them as one. The Margonite could be trying to empower the dragons, possibly using that magic of the bloodstones and the ley line to bring back Abaddon or just to cause chaos amongst Tyria.
When/if Mordremoth rises, the power of the bloodstones (previously not corrupted by the dragons) could be absorbed and make an even more powerful dragon.
Now, the White Mantle and Mursaat come into perspective because the White Mantle used the bloodstones to sacrifice people and use their souls to power soul batteries to keep the Door of Komalie (bloodstone) shut preventing titans to return.
ASIDE: Titans were the Gods of the Charr (Flame Legion) which would explain why they would want to help Scarlet possibly release Mordremoth/Abaddon and bring the return of the Titans. Nightmare Court could want Mordremoth because possibly the Nightmare is linked with his presence. Also, ascension in GW1 was introduced shortly before the Mursaat and infusion helped you fight them. And as we got farther into the living story, bloodstone dust became more abundant. It could be that even now Mordremoth is consuming the bloodstone and the “dust” is what is being spread out as a result to Tyria through the Ley Line.
White Mantle isn’t necessarily all dead. They could still be living somewhere on the Isles of Janthir where they could be living with Mursaat.
So, my insane plot line for this living story is as follows: Margonite are attempting to resurrect Abaddon by harnessing the power of the Elder Dragon Mordremoth and uniting all 5 of the Bloodstone fragments. Thus, as we push further into the Wastes we should see more and more references to Abaddon and the power of the Bloodstone. Once we reach the bloodstone, we will find White Mantle and possible Mursaat guarding it. This could open up new paths (leading us up to the Isles of Janthir or down into the Ring of Fire) while the Zephyrites return to the Crystal Desert or Labyrinthine Cliffs. This can go one of either two ways: either the Mursaat/White Mantle can become friends or foe. It wouldn’t be the first time that an evil race became good (Charr from GW1 to now for example). This would open up new races/classes/maps.
I’ll just put back on my tinfoil hat and go back to wandering aimlessly in the Silverwastes