Gamasutra has a very impressive and insightful interview up with Mike Hayes, president of Sega West. They talk about the future of Sega, where Mark Hayes says that Sega constantly has to strike a balance between reinventing old IP and doing completely new stuff. They go more in-depth with the Sonic franchise, talk about how there are actually two very different fan-bases and how hard it is to keep both of them satisfied. It gives you quite an interesting insight into Sonic 4 and Sonic Colors, so I’d suggest you check the interview out!
As far as I’m concerned, I agree with Mark Hayes! Sega has to concentrate on new IP in order to stay relevant, and some of the most interesting games from Sega are completely new IP, if we take the Platinum games and the like into consideration. Heck, some people think all Sega does well at the moment is publishing Platinum Games’ titles.