The ratings board describes the sixth WiWare game as a "musical paddle game in which players move a vertical platform to deflect waves of dots that fly across the screen." In addition, "musical tones" accompany each successful deflection. In other words, it's the same kind of extreme Pong we saw in Bit. Trip Beat. With similar gameplay, but in reverse (the screens show the paddle on the right side, whereas it was on the left in Beat) Flux appears to work with Beat to bookend the series.
Even so, we expect a few significant surprises out of Gaijin Games (if it's possible to expect surprises) as no two games in the series have had even remotely similar gameplay to date.