Miracle Kidz is working on a sequel to River City Ransom and they even have some of the original staff developing it. This news broke earlier this week sans one key detail, which console(s) will get River City Ransom 2.
The answer is Wii. River City Ransom 2 will be available on WiiWare in Japan this summer. A PC version is also in the works, but slated for release next year.
An interesting decision since Downtown Smash Dodgeball, a dodgeball game with the Kunio crew, was originally an Xbox 360 title. Miracle Kidz self-published it on Xbox Live Indie Games. A port of Downtown Smash Dodgeball is coming to WiiWare this May.
So far, River City Ransom 2 and the WiiWare version of Downtown Smash Dodgeball have not been announced for North America. An English localized version of Downtown Smash Dodgeball is available on Xbox Live right now, though.