New Relic Questline Prediction.

[Seraphor]

the MSQ might linger there for the remainder of the .X ...

My personal bets are in that the Void will be the setting for the new ... Trial series...

Mostly likely both. MSQ and the trial series.

We're going to the Void partially, or even mostly, in search of Azdaja.
Golbez is known for having a pet Shadow Dragon.
This isn't a coincidence.

Golbez is going to be heavily tied to the MSQ for the 6.x patches, and at the same time, he has the perfect candidates for the trial series.
So we're most likely going to get the trial series as part of the MSQ, much like 2.x.

My expectation is: three of the four archfiends will be trials, the fourth will be a dungeon boss, the remaining trial will be against Azdaja herself. Golbez will be a solo duty in 6.5, after which we see his face and true identity (an original character), and the MSQ leaves the Void. Golbez under his new alias then becomes the main villain for 7.0 as he comes to and poses a threat to the source.
There's still so much ground to cover before we know what form that threat takes, but as an early guess: the 6.x MSQ ends with us unlocking shard travel, and new-Golbez uses this new ability to bring chaos to the source in an effort to save the thirteenth, and revenge against us for killing the archfiends.