The End of the Plurimi

For as long as there has been sentient life in the world of Issolum, the Plurimi have been known. All citizens and creatures know the Plurimi exist. Benevolent creators of life, most choose to praise them and devote their lives to them. Many will build altars to them, and attend a church dedicated to all or perhaps a particular Plurimi. Religion is no question in this world.
Even still, there are those who foretell the end of the Plurimi. Some who speak of this claim to be prophets, linked to the Infernum, or perhaps believe that the Plurimi are not so benevolent as the rest of the population says. Often times, they will refer to religious writings that point to the eventual end of the Plurimi. These are ancient texts, recording the sacred word of prophets and priests that were revered as close to the Plurimi themselves, communicating with them on a regular basis. These texts are collectively referred to as the (Book of the Plurimi).
There are various verses that speak of the possibility that the Plurimi, as divine as they are, may come to an end.
This has two main variations in myth.
The first tells that the Plurimi will fade away from existence, or be defeated by another force. The Council of Thirteen are not invincible or eternal. They can be found on the celestial plane and struck down by a powerful foe. Some say that one will rise to complete this task, while others for see an army coming to bring this prophecy to pass.
The second variation says that the Plurimi will eventually abandon the world of Issolum. As time passes, the world will become corrupt, and the Plurimi will sigh, bow their heads, and leave this world to its decaying fate. They will make no attempt to save their creations, and will simply move on to create another world. Mortals, immortals, fey, magic, all will be left to wither away.
These are the myths, the prophecies, the words of the ones who warn the rosey-eyed. Will we ever learn if they were right?