And also representative of Terra and Riku's connection.
-- What's the meaning behind the several puzzling images in Terra's chapter where we cross over into his mind?
Nomura: Firstly, when he hears the name of the masked boy from Master Xehanort at the mysterious wasteland, and we see an image of Aqua and Ventus defeated, that's a hint of the future. On the Destiny Islands, when he makes Riku his successor, he has a special view of him and catches a glimpse of his future. However, this isn't to say that Terra has the ability to see the future - it was a directive nuance intended to portray the future connection between Terra and Riku.