Japan is getting an update for My Pokémon Ranch next month. It will add a few expected things, such as compatibility with Pokémon Platinum and the new Pokémon therein. For players without Pokémon Platinum, there’s at least one reason to upgrade anyway. The update will bump the maximum number of stored Pokémon from 1000 to a cool 1500. Protip: You will never have a use for 1500 Pokémon.
There’s no plan for a North American release yet, but I’d bet my metaphorical hat that America will see the update when Platinum launches.

