Well, Kishi did potray Sakura as playing a role in the sealing, at least symbolically. Even if she didn't play any direct role in the sealing, I think Kishi intended to show the Earth symbolism by the above. Kishi has perhaps used this Three celestial symbolism before :- Green Rectangle - Sakura - Earth Seal. Blue Rectangle - Naruto - Sun Seal. Red Rectangle - Sauske - Moon Seal. It could be possible that the Earth Seal will be Sakura's powerup. But that sign in Astrology represent the Sun not the Earth
