It will be hard to them to release a new sonic game when Impulse the zombiehog has redefined the playfield
To be fair my little exercise will be far outdo by the many 3D sonic community project. Once Sonic GDK will be done and release for open source or sonic runner will be complete, or the blitzsonic scene finally reach maturity (remember kids grow up and sharpen their skills).
Recent 2D project like Sonic Fan remix show the fan got it, and some are unreleased (sonic fusion). SO far sega tolerate fan gaming, but I guess as they project mature, it will start to take shadow. And lately some high skilled people join the community on project (animator, film maker, graphic designer, musician) attracted by the quality project that get some steam.
I do not how other sega games fare, but I know there is pretty big community that worship old sega.
I think Fangaming is one of the next big thing in video games, more and more mature skilled artist do it, it's part of of the gaming culture.