Urriak Uruk
Gaming is fun, and fun is for everyone
5e already slavery in it.
DMG page 19: "The cities of High port and Suderham in the Greyhawk campaign setting are satrapies controlled by agents of a vicious gang of marauders known as the Slave Lords."
DMG page 54: "The largest cavern beneath the mountains, called the Great Dismal Delve or the Sevenfold Mazework, is home to the capital city of the dao, the City of Jewels. The dao take great pride in their wealth and send teams of slaves across the plane in search of new veins of ore and gemstones to exploit."
DMG page 56: "The heart of the city is the towering Charcoal Palace, where the tyrannical sultan of the efreet reigns supreme, surrounded by efreet nobles and a host of slaves, guardians, and sycophants."
DMG page 100: "...and slave pens might be common features in a vault built by drow..."
DMG page 113: "Hidden slavers' den"
PHB page 24: "Drow grow up believing that surface-dwelling races are inferior, worthless except as slaves."
PHB page 40: "Other scars, though, mark an orc or half-orc as a former slave or a disgraced exile."
PHB page 94: "A human lurks in the shadows of an alley while his accomplice prepares for her part in the ambush. When their target-a notorious slaver-passes the alleyway, the accomplice cries out, the slaver comes to investigate, and the assassin's blade cuts his throat before he can make a sound."
Eberron Rising page 24: "When humans first came to Khorvaire, they enslaved many goblins and built their cities on the foundations of Dhakaani ruins."
Eberron Rising page 112: "Most of the Cyran population fled the goblin uprising, and those who remained were killed or enslaved." and " Others despise non-goblins. Lhesh Haruuc has abolished slavery in Rhukaan Draal, but some of clan lords continue this practice."
I could go on and on. 5e need not avoid and seems very willing to include slavery in its products. Dark Sun wouldn't need to be redone.
I literally gave Out of the Abyss as the example for how 5E has slavery. I know it does.
Still, slavery is such an overwhelming, constant presence in DS that there should be at minimum an option for DMs to write it out. There should explicitly be a "warning DMs" section, much like how Ravenloft does, that gives pointers on how to handle the topic or cut it out if necessary.