One of the biggest drawbacks of the original DS was its lackluster (or non existant, depending on the model) online store. The DS had a ton of games, most of which are buried under a lot of 3rd party shovelware or Nintendo's own titles. Titles like Megaman Zero collection, nine days nine persons nine doors, Grand Theft Auto: Chinatown Wars, Castlevania: Dawn of Sorrow, the original Etrian Odysseys... were lost to a potential audience because of their limited distribution.
Enter the 3DS. The system is backwards compatible with its predecessor, and has a much better eshop. So I was disapointed when I couldn't download full DS titles. It's not a problem of power, software or size (i'm sure most indies on the 3DS are bigger than a lot of DS titles).
But with the N3DS, we may have that option. Imagine if they release a VC for the DS on the N3DS. Inmediately the system wins hundreds of titles that are not selling now, but people have interest on them. What do you think? Will Nintendo release a DS emulator for the 3DS or the N3DS? Is that investment worth the efford? Which DS titles would you like to see if this came true?
