Board Thread:General Discussion/@comment-7657843-20170412162555/@comment-679780-20170412170916

Well, if Classic Sonic represent the past and Modern Sonic represent the future then the third new character could either be the following:
 * Silver the Hedgehog with Dreamcast like gameplay.
 * A unique version of Sonic exclusively for the game. Either to represent Sonic's possible future or, if the game takes place on an alternate timeline, could be another version of Modern Sonic who failed to stop the Eggman Empire.
 * An entirely brand new character, probably with Dreamcast like controls.

For all we know the last two could be true, a new version of Sonic disguised as someone entirely new as a red herring for the player, though I'm personally hoping Silver the Hedgehog will be the third character to represent the future.