In an interview with Games Radar about Ace Attorney Investigations: Miles Edgeworth, Motohide Eshiro stated that he has no plans for DSiWare - until the demand is high enough that is. He also said some other restrictions are stopping them from bringing the game to the service.
GR: Given the recent WiiWare remake of Ace Attorney and the franchise’s serialized nature, are there any plans for DSi episodes or content in the future?ME: Right now we really don’t have any plans for DSiWare going on. Of course if the demand is high enough we’ll have to consider it, but we have to also consider the memory limitations for DSiWare and technical things aside from what the fans want. There’s a lot to think about unfortunately.
You can read the full interview here.
How would you feel about an Ace Attorney game on DSiWare? Would you rather have a full game on cartridge than it be downloadable?