No, a VC for the 3DS hasn't been confirmed. But it's a logical assumption to make. Nintendo doesn't like to let their games fade into the past as if they never were.
The Wii had a VC that went from Nintendo's beginning up to two consoles back (N64). Applying that logic to the 3DS and assuming handhelds will be included (since there were no handheld games on Wii VC), you have Gameboy and GBA games (GBA is two handheld systems back, just as N64 was two consoles back from Wii), as well as possible NES and SNES games. Since the Wii is still going though, I kinda doubt there will be NES and SNES games. But GB and GBA games are very likely.
Anyhow, the main reason I want the 3DS is for the games, of course. Paper Mario, Mario Kart, OoT 3DS, Professor Layton, Animal Crossing, the list goes on and on <3