According to a report by Jonathan Holmes, an insider in the industry, Nintendo has no future plans with two of their franchises. While neither are particularly surprising, it's still sad news. According to Holmes, there are no plans to localize Mother 3 and release it outside of Japan, and there are no plans for a future Rhythm Heaven title. This is because Iwata was the only big advocate for these two titles, and with him gone, nobody at Nintendo has plans to continue with either series.
You never know what's going to happen, but the way it looks right now, under Nintendo's current administration, Mother 3 will never leave Japan and there will never be another Rhythm Heaven game. Iwata was a driving force behind the Rhythm Heaven series, and a consistent advocate for NoA to at least look at the possibility of Mother 3 finding a new audience in the United States and Europe. With him gone, there is no one at Nintendo pushing for either anymore.