netflix on the wii isn't moderately successfull, it's very sucessfull. It got more people to connect their Wii's to the internet then anything before it. 3D ntflix or movie streaming of some sort would be awesome for 3DS, even though we have already heard about the 3D movie functionality a bit already.
I do believe in the future 3D Netflix will be available. It's probably linked to that survey Netflix did a few month ago.