Shin’en has announced on their Twitter account that they are releasing Nano Assault EX on the Nintendo 3DS eShop:
‘Nano Assault EX’ is coming to the 3DS eShop (EU+US) ! Based on the original release but with new game modes & options.. more info soon!
The original release of Nano Assault at retail had some great graphics. Maybe having Nano Assault EX come to the eShop will make it sell better.