Square Enix might be reviving its Final Fantasy music series, as the Theatrhythm name has been trademarked in Australia and Canada. The Final Fantasy series has some of the greatest video game music tracks of all time, which formed the basis for the Theatrhythm spin-off titles.
The original Theatrhythm games appeared on the Nintendo 3DS. The player formed a party out of heroes (and the occasional villain) from the history of the Final Fantasy series, all of which could be leveled up and given special abilities. The games had three types of stages: a battle mode, an exploration mode, and an event mode. The battles involved hitting the touch screen at different points to whack enemies, the exploration mode involved following a track with the stylus, and the event mode involved following different directions. All of the stages used songs from the Final Fantasy series that were available up until that point, as well as a few from different Square Enix games that were sold as DLC. There was also a Japan-exclusive Theatrhythm Dragon Quest, which used songs and characters from that series.
The last Theatrhythm game was an arcade title called Theatrhythm All-Star Carnival from 2016, but that could soon change. According to IP Australia and the World Intellectual Property Organization, Square Enix has trademarked the Theatrhythm name in Australia and Canada. This suggests that the series is being prepared for a revival in a new form.
The fact that the Theatrhythm name is being trademarked on its own suggests that it could also become a new franchise that uses songs from the entire Square Enix catalog. The Final Fantasy series might have some incredible soundtracks, but Square Enix also has access to the music from games like Chrono Trigger, and whole series like Dragon Quest, SaGa, Mana, and Star Ocean. The Kingdom Hearts songs might be excluded due to rights issues, but the rest of the Square Enix catalog is ripe for the picking.
The most likely possibility is that Square Enix intends to bring Theatrhythm back as a mobile title. The gameplay would be a perfect match for the touchscreen format and there are lots of opportunities to sell characters and tracks through gacha mechanics. Mobile games have been lucrative for Square Enix, so it would make sense for the company to want to make more. The original Theatrhythm did receive an iOS port in the past, but it would be easy to make an expanded version of the game that used songs from titles outside of the Final Fantasy series.
Source: IP Australia, World Intellectual Property Organization