I could generally take or leave their clutter items, but persistent NPCs with dynamic schedules or the full stat and inventory systems of the PC are still extremely rare, never mind both. Most games simplify NPCs such that they don't actually have equipment or just have one item (typically an unlootable weapon) and reduce their stats to just HP and defense stats. By contrast, the only difference between an NPC and the PC in a Bethesda game is that the player has controll over the PC.

For me, if they moved to a new engine it would need those persistent fully-featured NPCs to feel like a Bethesda game. Ten years ago, there wasn't really anything else that did that. Now, there's got to be something they can make work. Hell, BG3 has all this stuff, it's just from a top-down perspective. And it can handle ladders, which Bethesda's engine still can't do.