Nintendo may have created the new Nintendo Network ID system, but that doesn't mean that all the game downloads from your old Wii won't transfer over. With the system transfer feature, you can move everything you've purchased—including unspent Wii eShop points—to the new system.
That means that those digital copies of Super Mario World, Majora's Mask, Castlevania IV, and Pokemon Snap aren't going anywhere. You can still get your retro game on with Nintendo's new console. We're even hopeful that they'll add support for Virtual Console games on the GamePad.