We covered recently that Sonic’s anniversary is leading to two promising titles with Sonic 2017 Project & Sonic Mania, but many are assuming that Sonic 2017 is a Generations sequel, considering Classic Sonic is present during the teaser trailer.
Sonic Team came out and stated that this is not a sequel to Generations and Nintendo Everything reported on this with the following comment.
The video showed both Modern Sonic and Classic Sonic in action. Does that mean SEGA intends to make the title as a follow-up sorts to Sonic Generations? Apparently not. Takashi Iizuka, a well-known developer inside Sonic Team, said that the new game is not a sequel. That would certainly rule out Sonic Generations 2!
Source: Nintendo Everything