The main problem with Sonic is that it has too many different audiences that they are trying to cater to :
you have sonic fans that only like 2d games
you have sonic fans that only like the boost gameplay
you have sonic fans that only like the adventure gameplay
and Sega has to make all those fans happy
They actually don’t have to keep them all happy because it’s impossible. Sega HAS to alienate one or more of those audiences in order for Sonic to thrive and it should be the ones stopping Sonic from evolving into a franchise that has mass market appeal.
2D games are fan service, Boost gameplay is iPhone quality gaming, they need to gut those two audience and make an experience that the fans of the movies would want to play.
As of right now, Sonic as a game has no identity, no core values, no consistent thread that ties them all together. You can pick up Mario Odyssey and do moves that were present in Mario 64.
Nintendo decided what Mario was going to be in 3D and stuck to it. Sega hasn’t done that with Sonic and it’s why they have these fractured audiences.
I hope they revitalize the gaming aspect of the IP with this next installment.