My own bias would be to wait for flowers (especially since the flowers should be happening in the near future), but I don't think the ID is wide open here. If the plant is K. luciae or thyrsiflora, it will have white or yellow flowers respectively.
The gray/white coating does not exclude Cotyledon as a genus (which one would expect to make colorful bell-like flowers like the ones on Tiffany's link) but it seems to be rather tall/old not to have flowered if it's a Cotyledon. Maybe indoors they behave different. The most common Cotyledons (the only ones I know from personal experience) flower every year without resulting in the death of the mother plant. They branch at the base of the inflorescence afterwards.
Anyway, all these things will play out in their own time and the answer should soon be staring you in the face.
Please share.
