What's the point with that quite lackluster story in Endwalker?

[Iscah]

I haven't done the Studium quests, but before you can claim that statement as proof of an eventual natural rejoining, it's important to define the "original state" that the currents are supposedly returning to. Are they talking about the pre-sundered state or simply the state immediately before both the pseudo-gods who have been stabilising the currents for millennia dissipated into the aether?

Also, if the aether currents are unique to each shard, then their state wouldn't directly have anything to do with them rejoining or remaining apart.

Narratively I think a natural rejoining would be very unlikely after they've staked so much on the value of the individual souls of each shard and that it would be a tragedy to lose them.

[Rulakir]

Still, I could see that rectification becoming something to 'stop', sadly. Unless it were to take place over a long time frame...

Unfortunately. Although, the only reason it was 'necessary' to be able to interact with dynamis was because of Meteion who's no longer a threat. However, I wouldn't put it past them to write Venat as having known this. Given her concern for the shards appears to be little more than collateral damage, it could hint that she knew the sundering would be temporary.

Yes, had they not destroyed a number of stars in pushing the plotline they did, that may have been less of an issue. Now they've pretty much just got the reflections and maybe more distant stars.

I hadn't thought about it, but you're right. I'm not keen on visiting other planets that have nothing to do with Etheirys. It was different in WoW where Outland was integral to the history of Azeroth, but the only places I know of in FFXIV where that might be true would be the dragon star and possibly Omega, both of which were used in EW.

Narratively I think a natural rejoining would be very unlikely after they've staked so much on the value of the individual souls of each shard and that it would be a tragedy to lose them.

It depends on how it's written. More personal headcanon, but I like the idea that the aetherial sea between the Source and the shards is re-connected, so those who die on the shards end up funneled back to their original souls. Eventually, this leads to everyone being whole again and reborn on the Source.

I suppose I should've clarified I see this as a long process, not a sudden boom all 4-5 shards collide into the Source causing the calamity to end all calamities. The Ascians may have found a MO that worked through polarization necessary to break through the barrier, but without that being the case now it might just be a slow trickle of aether from each one back to the Source that takes ages to even be noticeable. Probably starting with things like reduced magical ability and eventually lifespans. Once everyone's funneled back to the Source, by the time the shard fully rejoins there likely wouldn't have been anyone living on it for years due to the decreased aether. All just speculation though. :P