Dragon Age 4 hasn't been officially announced yet, but there are some pieces of Dragon Age lore that is likely to be relevant for the upcoming title. Namely, the lore of the Golden City and that of the fall of Arlathan, the great elven empire that supposedly fell to Tevinter.
However, history can have many different retellings, and as players have learned over the course of the current three Dragon Age games, not everything was as it seemed when it came to both elven history and the humans'. Therefore, it's time to go over the evolution of the lore of both the Golden City and Arlathan, and how that'll become relevant in the future for Dragon Age.
The Golden City
First off, Dragon Age's Golden City is actually now known as the "Black City," due to the interference of seven ancient Tevinter magisters. Long ago, the Golden City was supposedly the seat of the Maker, and the heart of heaven within the Fade. Depending on religious perspective, the Golden City could also have been the seat of power for the Old Gods, rather than the Maker. Elves also believe that their gods remain trapped in the Eternal City in the heart of the Beyond (the Fade), while humans believe that the Maker abandoned the Golden City due to the sin of his children in worshipping the Old Gods.
As the story goes, after the Maker abandoned the Golden City, leaving it to the Old Gods (or the elven gods, again depending on perspective), the Tevinter magisters known as the Magisters Sidereal, each a High Priest to one of the Old Gods, traveled directly into the Fade and physically entered the Golden City using blood magic. Once inside, as human legend goes, the city turned black and the magisters were cast back into Thedas as the first darkspawn.
From here, there are two critical pieces of information from the games to note: in the Warden's Keep DLC for Dragon Age: Origins, Avernus states that the Black City contains "an answer to what the [darkspawn] taint is." Second, there's the testimony of Corypheus, the big bad boss of both Dragon Age 2's Legacy DLC, and of course Dragon Age: Inquisition. In his Legacy encounter with Hawke, Corypheus claims that history has one point wrong; the Golden City was already blackened when the magisters entered it.
Together, those pieces of information about the Dragon Age timeline and history could have some major implications for the future of Dragon Age concerning the darkspawn.
Currently, the Black City is supposed the be the home of nightmares and darkness, sitting atop an island and studded with cold and twisting spires. It's always visible at a distance within the Fade, though it's easily the closest during the Here Lies The Abyss quest in Inquisition. According to the Canticle of Light (a verse in the Chant of Light), the Black City has seven gates, and Kordillus Drakon I once prophesized that they would someday shatter, covering the mortal world and the Fade in darkness. Once again, that's an important hint to keep in mind for the future.
Arlathan
Arlathan is the fabled elven city (literally translating to "Place of Love" in the elven language) that made up the heart of the ancient elven empire that spanned from Ferelden to Orlais and even the lands west of Orlais. Although the elves of old supposedly built many cities within the empire, most Dalish legends focus on Arlathan itself as a central hub of knowledge and elven culture.
Thus, when the Tevinter people began to try and conquer the elves, they focused they powers on Arlathan, using an army of mages, demons, and dragon thralls to breach the gates and storm the city. As the Dalish stories tell, rather than stand and fight, when the gates of Arlathan were breached the ancient elves chose to flee, and were consequentially enslaved by the Tevinter invaders. Tevinter magisters then used their magic to actually cause Arlathan to sink into the ground, effectively toppling the elven empire once and for all; due to their extended contact with humans, the elves' blood "quickened" and they became mortal.
As for the fall of Arlathan, while generally its physical fall is attributed to the Tevinters, the elven people also blame the trickster god Fen'Harel, the Dread Wolf, for their peoples' plight. According to the elves, Fen'Harel tricked the other elven gods and sealed them away inside the Fade (as mentioned above, with the gods being sealed inside the "Eternal City" of the Fade). Thus, the gods were unable to come to their peoples' aid when the Tevinters invaded, leading ultimately to the downfall of the elves.
However, Fen'Harel is revealed to be Solas in Inquisition, and he has a different take on the fall of Arlathan. According to Solas, he led a rebellion against the rest of the gods (save Mythal, a close friend of his who was murdered by the other evanuris) over their abuses of power and enslavement of some elves. During this rebellion, Solas came to believe that the only course of action he could use to end the war was creating the Veil, sealing the gods in the Fade and drawing Arlathan and the rest of the empire fully into the mortal realm.
In Skyhold, his castle, Solas performed the magical ritual that created the Veil and separated the Fade and Thedas; he caused the quickening of the elves' blood, leading to their mortality, and he was ultimately responsible for the destruction of Arlathan. What does that mean for Dragon Age 4? Potentially, lots of things.
Lore Parallels
Given all that, it's possible to draw some parallels between the lore of Arlathan and the lore of the Golden City--parallels that suggest Arlathan and the Golden city may even be one and the same, supporting the idea that the evanuris are trapped inside it right now, and may even be the main antagonists of Dragon Age 4.
First, there are the gods; there are seven trapped elven gods, seven Old Gods, seven gates to Arlathan. The elven gods might even be the Old Gods, or at least parts of them, as demonstrated when Flemeth (Mythal) seemed to absorb some power from Keiran (who has the soul of the Old God Urthemiel) during Inquisition. And, when Drakon predicted the seven gates of the Black City would shatter, he could have been predicting the Dread Wolf's current plans to destroy the Veil and once more bring the Fade and Thedas together, destroying the world such as it is today. Not only that, but there is evidence in elven legends that the evanuris may have been responsible for first bringing the darkspawn taint and red lyrium to the world from the Void, so it would make sense that the Golden City was already blackened when the tevinters arrived and that they were subsequently infected with the darkspawn taint.
Either way, it's clear that the Golden City, Arlathan, the darkspawn, and ancient Tevinter are all entwined in some mysterious way, and odds are we'll find exactly out how in the long-awaited Dragon Age 4.
Dragon Age 4 is confirmed to be in development for the PS5.