Been trying to resist doing a double-post-in-thread-I-started deal, but had a couple of other bits cross my mind that don't fit in other threads.
First, keep thinking back to The Twinning and how a variant of Alexander wound up being the boss. At the time just kind of went "oh that's odd" but looking back I think that's going to be really significant. Emet-Selch had a whole conversation with G'raha about how the Crystal Tower and Allagan technology by rights shouldn't be enabling time travel or interdimensional physical teleportation between shards as the WoL/D manages. And G'raha gives a weird non-answer when he asks.
I don't think we've seen the last of bizarro time/space travel. And while I might be wrong/take this speculation with a big grain of salt, I'm starting to suspect we might not have even seen the last of Emet-Selch.
Technically speaking I can think of two straightforward ways he could come back without breaking with logistics of the universe, one tying to the clone bodies (which were emphasized too hard to just get discarded offhand imo) and one with the Alexander stuff. I also am suspicious because while it's possible Amaurot will simply degrade in similar fashion to the Warring Triad statues in Azys Lla (trees are already dying :<), the fact that there are shade vendors and NPCs to talk to has me unbelievably suspicious. That and they built his character up insanely, insanely well and it would surprise me a little if he was gone this fast.
I don't mean any of this in a wishful-thinking way, knowing the guy got popular. After finishing MSQ I just went "well he's dead and gone and that's done" but now I'm starting to wonder a little. Especially since Minfilia pulled so many weird sticking-around moves on this front too.
Slightly different note, Lahabrea being a really powerful Amaurotine creation specialist and doing so much ritual stuff reminded me of the fact that he oh-so-dramatically exclaimed that the Ultima Weapon was powered by the Heart of Sabik, demonstrating a fraction of Zodiark's power.
"WHAT THE HELL IS SABIK????" has become a question that keeps me up at night, and if this doesn't come back and get addressed I don't know what I'll do with myself.
At this point I'm starting to wonder if it's the heart of one of Lahabrea's coworkers in the Convocation of Fourteen who sacrificed themself to Zodiark, but it's still wild speculation.