SEGA Japan’s Sonic Channel has launched a “Sonic 2020” initative, which will announce something new that is Sonic-related on the 20th of every month in 2020. This project is January 20th’s announcement. The official page can be found here.
So, the obvious question: will this announce the next Sonic game? Well, they say that they will “hold various Sonic the Hedgehog-related events in 2020″, and they do suggest that fans “keep an eye on the franchise as it approaches its 30th anniversary in 2021”. So, it’s possible.