MSQ Spoiler/Speculation
Fundamentally, it seems like the story is heading for a reprise of the original Warriors of Darkness arc: when is being "too good" bad? The "flood" of new Warriors of Light literally threatens to return the flood of light and usher in the long-awaited rejoining. But how are we, basically the champion of doing good, supposed to stand there and tell people not to follow in our footsteps? Faced with all these well-intentioned people, are we supposed to turn around and really wear the "Warrior of Darkness" mantle and fight the Warriors of Light for the good of the world (and so become the "villain" in an effort to be the hero, as the Warriors of Darkness once attempted)? (Considering it was Elidibus who put them up to it, it's obviously thematically appropriate.)
Regarding Hydaelyn and the "voice" everyone heard after the starshower "trigger," I'm wondering if this might be sort of like an "automated program" -- sort of like a recording that automatically plays to anyone given the signal and with the potential/desire to do good. So what they heard isn't the "living" voice of Hydaelyn (who, as everyone noted we haven't heard from in a long time), but just the forced activation of the "beacon." Elidibus is spreading this sort of like a virus, and it's presumably because the true "living" voice of Hydaelyn is too weak to directly intervene (and there are "programs" like this in place specifically to prevent her from having to personally intervene all the time; all she normally needs to do is initiate the trigger). This sort of helps to reinforce how the situation with the original Warriors of Darkness could happen in the first place; they would never have "progressed" to the state they did without a push from Ascian influences, as we see happening here, and Hydaelyn sending Minfilia to stop the flood strongly suggests this was never Hydaelyn's desire/intention.
If we combine this with what we learned about Venat being the "heart" of Hydaelyn, perhaps we can speculate that Hydaelyn's vessel, just like her solution of the sundering, is flawed in that it can be manipulated by people who know how to game the system (Ascians). But although this is the case, we have evidence to suggest that Hydaelyn's *intention* -- the heart of Hydaelyn? (Venat?) -- is fundamentally in alignment with our own desire (to protect sundered life from being sacrificed to Zodiark). So the problem here isn't people's desire to do good or help others, it's that they're being artificially manipulated to do so by Ascians (who are abusing, among other things, Hydaelyn's own "program" to do so). The Ascians are going to argue Hydaelyn's calling is also an "artificial" way of manipulating people, but left alone it seems to default to a natural equilibrium, and not just endlessly activate more and more champions ad nauseum -- it's basically only there because Zodiark needs to be opposed.
I think all this seems to be leading to a place where (eventually) we stop Zodiark but also put Hydaelyn to rest -- in essence to truly leave the world to the lives newly-born. This will allow the story to thread the needle about why being on "Team Hydaelyn" was ultimately good all this time -- it was necessary for the ultimate purpose of not allowing the Ascians/Zodiark to win, and our ultimate desire to do good was aligned with Hydaelyn's "heart" if not all the effects of her imperfect "programming" (especially when manipulated). By sealing the "blessing of light" for good, it also helps to serve as a sort of soft power-creep reset for the next story arcs, as well as cut the power source off from a lot of recurring villains.
I guess the real question I have is how much of this gets wrapped up in the next patch (to close the Shadowbringers arc) and how much of it remains open to deal with in the next arc. At this point the main required order of business seems to be: 1) the Scions awakening from their plot-necessary (?) stupor to realize what Elidibus is up to, 2) finding a way to turn the well-meaning "Warriors of Light" back to a path that doesn't cause a flood of light, 3) stopping Elidibus (to prevent him from continuing to try to cause the rejoining by manipulating the First), 4) getting the last missing pieces about Hydaelyn and the past, and 5) getting the Scions back to the source before their link is permanently severed (since the clock is ticking). Even they do stop Elidibus, that itself wouldn't close out Zodiark/Hydaelyn or whatever other sundered Ascians exist (like whoever is possessing Asahi), it'd just leave no one to elevate more new Ascians, so the rest of the clean-up could in theory happen in the next plot arc.
All that aside... the reveal at the end about Zenos is interesting. Given Emet-Selch's obsession with remembering the past and his efforts with the Amaurot reconstruction, the idea that he could find a way to implant these memories in Zenos (and maybe others in his lineage?) opens a few interesting doors, especially now that we know that the specific scene in his memory also serves as a "key." I still also haven't forgotten about the Solus clones and the whole soul transference stuff they were working on, so I wonder if all this is connected somehow.