I don’t remember anyone saying the WoP wouldn’t work. This was just that thralls will no longer be an item to pick up and carry.

I suspect the WoP’s will work similarly to shallow graves. You drag unconscious NPC’s and place them in the wheel, it then converts them to a thrall which pops out after conversion is done. Once they go in, you can’t get them back. This has precedent also with the shackles.