Nintendo is working on new features for the Mii Plaza, as well upcoming titles that will make use of the Miis.
New features will be making way to the Mii Plaza on the 3DS by end of this year, Iwata announced at a recent investors briefing. Iwata was asked about updates for the application, and he responded by saying that he has heard complaints regarding the lack of replay value and that Nintendo plans to update the Mii Plaza with new features later this year.
Iwata also remarked that Nintendo is working on titles that will make further use of the Mii Plaza.