Sonic Ruuuuumors: New Sonic is ambitious shelved idea brought back for PS4/XBO, Colors possibly to PC, SoJ did not intend Sonic 4 to be Sonic 4; SoA pushed it.

[IamAwsome]

Hopefully they develop a winning formula and STICK to it this time. One major problem with Sonic is that most of the 3D Sonics have different gameplay styles. At this point Sega doesn't have much left, so they really need a winner. 

As for platforms, there is no way this doesn't launch on a Nintendo platform. It WILL launch on one of NX/WiiU/3DS. If the gimped Wii version of Unleashed sold more than the PS3 and 360 versions combined, then they won't pass on Nintendo; power be damned.