Any chance of an eShop release is unlikely because of licensing issues to boot.
The likelihood of Retro Game Challenge 2 seeing an official release outside of Japan is slim-to-none, according to XSEED, the publishers of the first game in the series.
"Unfortunately with the number that Retro Game Challenge did, it’s close to impossible to justify bringing the sequel over," XSEED's Jimmy Soga told us.
The reasons don't extend to just sales, though. Soga shot down the likelihood of an eShop release because of licensing issues. "It’s true we really don’t have to worry about inventory if we bring it over to 3DS eShop," he said. "But it is a bit of a tricky title since the rights belong not only to Namco Bandai for the game, but also to Fuji TV for basing it off the television series."
Retro Game Challenge out on DS in Japan in 2007 and in North America in 2009. You can read our review for more details.
The sequel, featuring retro-inspired takes on games from the Super Nintendo and Game Boy eras, was published by Namco Bandai in Japan in 2009.
There is still a fan translation of the game reportedly in the works. However, the website hasn't been updated since early 2012.
Screen is from the fan translation project.