Rhythm Heaven is one of the most creative series owned by Nintendo. The way it mixes a fast paced minigame roulette with mastering of rhythm gameplay is unique itself. Many games stick to the classic "select the song and play it" without giving context, others make rhythm based adventure games -- Rhythm Heaven is different in that it gives context to the music (usually through fun scenarion), but without being a story-based title, making for a more casual yet deep experience.
One of Rhythm Heaven's biggest strenghts is the fact that it's produced by Tsunku, a famous musician, composer and producer in Japan (he was the producer for the famous idol group Morning Musume). He created Rhythm Heaven together with Nintendo, making the music and rhythm aspects very high quality. You're able to play Rhythm Heaven even with yours eyes closed because of the musical production being so well made!
Sadly, the series, while big in Japan, always suffered from lack of promotion and support from Nintendo of America. It seems like the north american branch has almost no interest in several of Nintendo's more "niche" or unique projects and prefer to stick to promoting the classic Mario, Zelda, Pokémon group of franchises, limiting the potential of several franchises (see the poor support they gave to series like Style Savvy or Fatal Frame).
A big example of this mistreatment is how the latest release was basically ignored and sent to death by NOA. Rhythm Heaven Megamix was launched in Japan in June 2015... it only got a NA release in June 2016. Even worse, it had basically no marketing -- Megamix was announced during Nintendo E3's Treehouse live segment and shadow dropped for the Nintendo eShop with no physical release, which even Nintendo of Europe provided for the title.
NoA's lack of interest in promoting a first party franchise seems pretty unjustfied and based on a conservative mindset ("this is too strange for american audiences") considering the selling potential the series has. It's a multimillion franchise even with only a few entries, the Nintendo DS title alone sold 3 million units worldwide!
Tsunku had problems with cancer a few years ago and had to remove his vocal cords, sadly. Megamix was released after that, but I wonder if the chances of getting a new entry go down because of this, even though Megamix did pretty well (over 700K units sold in Japan alone).
A great way to show respect to Tsunku's and the franchise's legacy is for Rhythm Heaven to be promoted on Super Smash Bros. Ultimate. The game is all about Nintendo's all star characters and series and Rhythm Heaven just makes sense to be there -- it's a popular long running franchise with the classic Nintendo charm. It's also know Smash Bros can renew/grow interest for Nintendo franchises and a good representation could lead us to more excellent Rhythm Heaven titles. A brand new original entry for Switch would be perfect as it would keep the portability of the DS/3DS titles, while being a good party game in docked mode.
It's heavily speculated that a Rhythm Heaven fighter was planned and scrapped for Smash 4 (probably for hardware issues), with leftover data for a fighter being found in the 3DS version of the game. Hopefully people can show support to the series for Ultimate. Even if it doesn't get into the base roster, there's always DLC! Maybe this can show to Nintendo (mostly NOA), that it's worth to keep investing into such a fun and unique franchise.
