What aligments would future calamities even have had?

[Lyth]

During the Eden questline (Shadows of the Past Lv.80), Mitron explains that calamities have a knock on effect on all shards, not just the Source. In fact, the entire reason why the First became so precariously Light-aspected in the first place was because of the Flood of Darkness. It stands to reason that the more rejoinings that happen, the more heavily aspected the aether of all the remaining worlds become. It's just the opposite of the process we went through to free Mitron's soul from Eden. It also suggests that each rejoining makes subsequent ones more likely.

I don't think that you'd have to manually rejoin every last shard to make the entire system unstable. It's a domino effect. I think this is what Hydaelyn was alluding to during patch 3.4 (Word of the Mother Lv.60). Otherwise, why did we have to worry about Zodiark being freed when we're a bit past the halfway point? Why did both sides commit all their resources to the First in an elaborate chess match? I think we're sitting right at the tipping point.

As for the elemental aspect of future rejoinings, it seems like we've had two darkness-aspected calamities. Everyone remembers the scene with Emet, but that's actually not the most important Crystarium scene. The one to look at is the earlier one from G'raha on returning from Alphinaud and Alisaie's respective questlines (The Lightbringers Lv. 70). The animation shows you what shards were destroyed and what the associated elemental calamity was:

First Umbral Calamity of Wind - Fifth Shard
Second Umbral Calamity of Lightning - Twelfth Shard
Third Umbral Calamity of Fire - Second Shard
Fourth Umbral Calamity of Earth - Third Shard
Fifth Umbral Calamity of Ice - Sixth Shard
Sixth Umbral Calamity of Water - Tenth Shard

All of these correlate with the elements listed in the EE. The interesting one is the Seventh Umbral Calamity (Seventh Shard), which isn't explicitly classified in the EE but from the animation seems to be Darkness aspected. We know that the Eighth Umbral Calamity would have been Light aspected. I wouldn't be surprised if any further calamities would be simply Light/Darkness aspected simply because all the Shards have had their aether aspected to every element by this point.

[Heroman3003]

During the Eden questline (Shadows of the Past Lv.80), Mitron explains that calamities have a knock on effect on all shards, not just the Source. In fact, the entire reason why the First became so precariously Light-aspected in the first place was because of the Flood of Darkness. It stands to reason that the more rejoinings that happen, the more heavily aspected the aether of all the remaining worlds become. It's just the opposite of the process we went through to free Mitron's soul from Eden. It also suggests that each rejoining makes subsequent ones more likely.

I don't think that you'd have to manually rejoin every last shard to make the entire system unstable. It's a domino effect. I think this is what Hydaelyn was alluding to during patch 3.4 (Word of the Mother Lv.60). Otherwise, why did we have to worry about Zodiark being freed when we're a bit past the halfway point? Why did both sides commit all their resources to the First in an elaborate chess match? I think we're sitting right at the tipping point.

As for the elemental aspect of future rejoinings, it seems like we've had two darkness-aspected calamities. Everyone remembers the scene with Emet, but that's actually not the most important Crystarium scene. The one to look at is the earlier one from G'raha on returning from Alphinaud and Alisaie's respective questlines (The Lightbringers Lv. 70). The animation shows you what shards were destroyed and what the associated elemental calamity was:

First Umbral Calamity of Wind - Fifth Shard
Second Umbral Calamity of Lightning - Twelfth Shard
Third Umbral Calamity of Fire - Second Shard
Fourth Umbral Calamity of Earth - Third Shard
Fifth Umbral Calamity of Ice - Sixth Shard
Sixth Umbral Calamity of Water - Tenth Shard

All of these correlate with the elements listed in the EE. The interesting one is the Seventh Umbral Calamity (Seventh Shard), which isn't explicitly classified in the EE but from the animation seems to be Darkness aspected. We know that the Eighth Umbral Calamity would have been Light aspected. I wouldn't be surprised if any further calamities would be simply Light/Darkness aspected simply because all the Shards have had their aether aspected to every element by this point.

Actually, that demonstration animation is rather unreliable source. It shows Ice Calamity (cyan) as last one before the Darkness Calamity, which we know is false, because last calamity was actually Water (blue).