Okay, so in a recent trailer/video clip, we've seen what appears to be Amon energybending/taking away the bending from Tahno. (Or who looks like Tahno) But there's a very distinct possibility that it isn't a form a bending at all!
(Appa girl, you've already heard this and therefore you can't make fun of it on here. :P)
So anyway, we see Amon placing his finger on a point on Tahno's head, much like Aang to Ozai. Now there is actually a very powerful pressure point called the Third Eye and it's located at this same point. The Third Eye is also where the Ajna Chakra is, which deals with things of spiritual matters. And Mike and Bryan (as well as many characters in the series) have indicated that bending is spiritual, (seeing as the Avatar is the link between the physical and spiritual world).
Anyway, we're pretty certain that Amon is a non-bender, as well as his followers. And I'm still sticking with that idea. (But how could he take away someone's bending if he can't even bend, himself!?) Very simple.
Amon and his followers are supposedly experts in the art of Chi-Blocking. And since simply hitting people at certain points takes away their bending temporarily and/or capacitates them, wouldn't blocking the Chi in the spot that is the most spiritual in the body take away bending permenantly?
Since this is seventy years in the future, I'm guessing the knowledge of Chi-Blocking has advanced greatly. Probably to the point where something like this could happen.
This would keep to the theory of Amon being a non-bender, but also have the ability to take away the bending of someone.
Maybe he's a decendent of Ty Lee?
I dunno, it's just a theory. But I think it's a strong possibility.