OK, I have got an idea of how to create a right Dark Sun version of Dragonlance. We start with an alternate timeline, explained better in the short story "There Is Another Shore, You Know, Upon the Other Side"
(Copied and paster from other web)
In this alternate timeline… the Kingpriest succeeded. He conquered not only the world… but the gods themselves.
This timeline begins when the Graygem of Gargath fell into the Kingpriest’s hands, everything changed. He no longer sought to cleanse evil—he sought to own the light. The gem, having trapped Chaos itself, gave him the power to command divinity. He bound the True Gods in mortal form, stripped them of their thrones, and declared himself the Godking of Krynn.
Under his rule, Istar became the center of all creation… and all who lived upon Krynn bowed to him. The world that followed was not destroyed by fire—it was consumed by order. From the shores of Ergoth to the deserts of Khur, every kingdom became a Dominion of Istar. The banners of the blue eye and golden sun fluttered above every city. Laws of purity replaced laws of freedom.
The Knights of Solamnia rebelled, but were driven down and broken by the magic of the Godking’s priests. They served as paladins of the Godking’s peace—hunting wizards, heretics, and any who defied Istar’s perfection. Everywhere, the Eye gazed down—the symbol of the Godking’s sight and judgment. It was stamped into coins, carved above doorways, branded into slaves. Even the heavens bore his mark.
The True Gods still existed, but they were broken— stripped of their power, imprisoned in mortal form.
...
And here the troubles go worse. Some humanoids hunted dragons, and when these were killed the hunters absorbed their power and acquired draconic features. Those were the origin of the overlord dragons. At least this is the official version. Really some dragons to escape their fate they put their souls and essences into magic jewels that would be used by the overlord dragons. Teorically these keep their free will and this is true but not totally true.
The necromancer Fistandantilus couldn't allow this and he casted a great ritual to summon some divine power what could help, and this divine help arrived, but not in the way somebody could guess. The summoned power was... the god Raistlin from the alternate timeline where he caused the cataclysm.
You can imagine during more a century where is a war not only in Krynn but in the rest of Wildspace. The tirany of the Kingpriest ended, but the sacrifice was so great that it was almost a Pyrrhic victory. The arcane magic couldn't work in the same way because the gods of the magic lost their powers and when Fistandalntilus discovered the defiler magic, you can imagine what was going to happen.
And if it was not enough, Krynn has got a parallel layer, Sithicus, like the Krynn version of the Shadowell, with its own dark domains. Here lord Soth earned his redemtion and he was forgiven, being something like a celestial construct and all the members of his family are alive (even his first wife and his firstborn) but he is rejected by his second elf due his evil actions in the past.
In Sithicus plants can survive and recover after suffering defiler magic, but they are "tainted" and humanoids don't want, and they shouldn't live near tainted zones because they could suffer mutations or "dark gifts".
