Thoughts on where things can go.(Spoilers involved)

[CaptainLagbeard]

"The Key" is very likely going to be a big piece of whatever is going to come next... As it had the the Sun symbol on it when it was activated by the Everqueen/Queen Eternal, that particular Sun symbol being Azem's astrological sign.
We also learned that it came to Alexandria from the Source during The Sixth Umbral Calamity, a.k.a. the great flood as it was used to open a portal by Lalafels on the Aloalo Islands to escape it.

The people over at whatever reflection Alexandria was in, were able to use The Key to open a portal to the Source. While we've only received confirmation it works between those two reflections, it doesn't mean it won't work on others.
And because of potential travel between reflections, I foresee Y'Shtola being present due to her interest in the subject.

[Kaecilius]

The people over at whatever reflection Alexandria was in, were able to use The Key to open a portal to the Source. While we've only received confirmation it works between those two reflections, it doesn't mean it won't work on others.
And because of potential travel between reflections, I foresee Y'Shtola being present due to her interest in the subject.

As a small detail, we know that they have also tried Interdimensional Fusion before, and that's when the Dreamborough (and other unnamed districts) ended up lost beyond the Rift, presumably on the Thirteenth for Strayborough Deadwalk (Though I don't think this is actually confirmed?)

Interdimensional fusion could be a key to fix the Thirteenth and the First, since they are heavily charged with opposite elements, absorbing excess light from the First to restore small areas of the Thirteenth, if such a thing is even possible.

[Xelanar]

I have an idea. It starts with "Speak with Wuk Lamat".

[Daralii]

We are Azem's shard. And it's entirely possible that Azem created the device possibly as their answer to the Final Days. Or they could have had prescience about either the Final Days or future events as was hinted in the Pandaemonium storyline when they told Themis a falling star would appear before him. And then we fell on him.

Considering Azem recommended us to Themis for confidential Convocation business, I wouldn't be surprised if they sensed the WoL's arrival in Elpis, observed magically, and learned about the future while being well out of Kairos's range.

[TaleraRistain]

We are the current iteration in the Source, but it's entirely possible Azem lived as someone else before, then died and they were eventually reborn as us. We also know that people from the Reflections can be targets for awakening as Ascians/Ancients, such as Gaia being the reincarnation of Loghrif.

Oh we're not the first. The Four Lords heavily hints that Tenzen is a past incarnation of Azem's shard. There would certainly have been others. That's just the only named one we've had so far.

Considering Azem recommended us to Themis for confidential Convocation business, I wouldn't be surprised if they sensed the WoL's arrival in Elpis, observed magically, and learned about the future while being well out of Kairos's range.

Entirely possible as well. I believe there was a recent interview where Yoshi-P said we weren't quite done with the Ancients yet and Dawntrail having an artifact potentially made by Azem would be an interesting way to delve more into that Ancient persona.