I agree with the downloading... Someone will eventually upload an "Avatar 3D" copy and if it's good enough, I will work. The limiting factor then will be the user's video card on the computer. I doubt it will be nearly as good as the theaters but it will still have some of the effects.
I was talking to this home theater owner who we worked with for a while and he was saying that 3D WILL work perfectly fine and great with these new 3D generation televisions, but the only problem is that 3D is a MUCH MORE fulfilling experience on a SUPER large tv rather than like a 40". Something to think about...