No other information was given, however.
With the incredible Sonic Mania (and then Sonic Mania Plus), Sega has finally managed to bring the franchise back to a level where fans are actually excited to see where it goes next, rather than dreading to see how it screws things up even more. Questions about when we might see the next mainline Sonic title have been on the minds of many people for some time now, and as it turns out, Sega has answered those questions- well, to an extent anyway.
At their SXSW Gaming 2019 panel, Sega’s Takashi Iizuka, who is the head of Sonic Team, announced that the next mainline Sonic title is now under development. He didn’t go into any other details- a release window, a title, target launch platforms, or what kind of a game it’s going to be. But it’s coming. It’s cooking. We have something to look forward to.