According to Variety, we will in fact be getting that Sonic Movie sequel!
Jeff Fowler will once again be directing and Pat Casey and Josh Miller writing. Hajime Satomi, Haruki Satomi and Tim Miller will be executive producing while Neal H. Moritz, Toby Ascher and Toru Nakahara will also be producing.
Little else is known such as the title of the film and its expected release. If we had to guess, Sonic The Hedgehog 2 would fit the bill. And then we just need the 3rd movie, which would introduce Knuckles be titled Sonic The Hedgehog 3 & Knuckles. It just has to be!