The game featured in the below video, which features characters from the long-forgotten Street Fighter EX series, is fully playable, says Arika's Ichiro Mihara. In fact, the game was playable at an exhibition event in Japan, though Mihara was a bit concerned that no one was going to show up because everyone thought it was fake since the new game was the focus of that event. People did show up, and the video has been making the social media rounds, with a decent amount of success.
It is quite possible that we will in fact see this game released some day if reception is hot enough. For now, it seems to be an event-only sort of game and has only appeared in Japan. Hopefully we'll see it stateside sometime soon.