Although Naxxramas has never been outright removed ... It was also re-tuned to become an appropriately leveled raid for the expansion, rather than remaining at the level of Classic endgame difficulty.

Even the WoW Classic Season of Discovery 2025 Roadmap was vague. It said “Naxxramas Raid, New End Game Content…” Whatever was going to be, has clearly changed, and that’s for the better.