It seems The Ringed City holds parallels with the orb/egg that the sleeping Filianore holds. Now, we know Gwyn "gifted" his daughter to The Ringed City, but we also know The Ringed City was kept away from the rest of the world to contain the pygmies.
We know the pygmies were the original humans, those who discovered the Dark Soul at the dawn of the age of fire. Gwyn feared the coming dark/end of the age of fire so locked them away, right? He and the other gods weren't particularly fond of humans or how they pushed the Age of Dark (knowingly or otherwise), hence the curse, the Asylum, Darksign etc.
We also know Gwyn's lineage possess the ability to create illusions or maintain alternate realities (Anor Londo, possibly the Painted Worlds).
Filianore was given to the city, however could it be that he did so not in a benevolent manner, but to use her abilities to prevent the dark escaping, the pygmy kings to encroach further into the rest of the world bringing on the Age of Dark?
The whole city has these large, dark crystals (similar to the Dark Gems we find throughout the series), and those are seen in the core of the damaged orb/egg. The orb/egg may well be the physical representation of the "barrier" of The Ringed City, locked away in the hands of a heavily guarded Goddess Princess.
Now, at the end of time, possibly through the actions of yourself, Gael, or slow decay, the orb was cracked and damaged. Upon being touched (by a human of sorts to boot), it crumbles, "awaking" Filianore and seemingly fast-forwarding time to show a fire-less Age of Ash, not quite an Age of Dark, "ruled" by the pygmy kings. It isn't the dark place that Gwyn feared all along, it's just the ashes of the world.
Enter Gael — Who wanted to obtain the Blood of the Dark Soul to create a new painting, to allow the Painter to start a new world: "A cold, dark, and very gentle place". The Age of Dark. The entropy, the "peace" and stillness that the Age of Dark was always said to bring. It happens through Gael and ourselves, but not as Gwyn et al. imagined, or even how we thought.
What if the Dark endings of DS3 (Usurpation/Lord of Hollows) actually only usher in an Age of Ash, one without the First Flame and the gods, but not immediately the Age of Dark. It would let the pygmies, hollows and locusts feed on the bones of the world, but not directly result in their ultimate goal? Without fire, would the world return to a grey age, like when the Everlasting Dragons existed? That isn't the Age of Dark. There cannot be Dark without Light in that place. Perhaps the painter's vision is to create a dark world entirely — Requiring seeing the "flame" and light in order to paint a dark flame, using the Blood of the Dark Soul as the pigment for this new First Flame?
On a side note, while we hear Ludleth is from Courland, his title is Ludleth the Exiled. He's also clearly a pygmy, burned from linking the First Flame or not. Judging by his demeanour and oldschool English, he's ancient too. Then, we find out he's a student of transposition: The forbidden art of extracting a soul and turning it into something else, for which he was likely banished (and perhaps how he lost his legs and was burdened with the Skull Ring — Which we find rather than transpose, meaning he carried it).
What if, then, Ludleth was one of the pygmy kings, who wished to "paint a new vision" to them — Perhaps he believed the Age of Fire should not end; or perhaps after his exile, perhaps he wished to spurn his kind and prolong the Age of Fire to spite those who scorned him, to keep them trapped in their Ringed City.
Just some rambling theory to chew on.