What aligments would future calamities even have had?

[Iscah]

The Thirteenth was written off, so we already know that it's not required for ALL shards to be rejoined, a partially rejoined Source would be sufficient.

We still don't know for certain whether it was not required, or simply put in the "too hard" basket while they work on rejoining the other shards.

For all we know so far, it's possible that they were manipulating Golbez into eating the local Zodiark shard and then breaking through the barrier into the Source, bringing Zodiark's missing piece with him. Or maybe that shattering of the barrier would be enough to hook the Thirteenth back up to the Source's lifestream. Those are certainly the sorts of plot holes I'd be trying to fill as a writer at this point.