I think it's safe to assume something bad is gonna happen to Sora.
Nomura likes his symbolism. In KH1, Riku was the only one facing the opposite direction of Sora and co.
Imagine if Sora fails to return to the RoL, and the first part of KH3 you play as Riku, or maybe even Ven(saved from sleep in KH3D) to save Sora. Would be pretty epic. I don't think Nomura will fail to surprise us.
Or perhaps, as the official page presents, one of the two characters that are currently blank next to Sora & Riku is Mickey, and the first part of the game you play as Riku/Sora. Riku manages to get out of the RoS but Sora does not. Then the next part Mickey enters and has to save Sora. This is getting exciting.