Bioware is creating Sonic Chronicles. So even if Sonic Chronicles exceptionally well, it wont really effect Sonic games in the future, unless Bioware continue with Sonic.
However, if Sonic Unleashed does turns out to be great, then that's just a step in the right direction for Sonic Team. If it turns out to be average or another dud, well.... Back to the drawing board >.>
But to be honest, Sonic Unleashed is looking good. It's combining both gameplay elements of Sonic Rush, which has a faster paced feel to the genesis titles, and the gameplay of Secret Rings which was a decent spin off for Sonic.
I was disappointed when IGN said in the preview that there will be no multiplayer what so ever (I've always wanted a competitive online Sonic/Racing game) and that it runs at 30 frames per second (kinda weird for a game where your traveling at high speeds @.@), but it really all comes down to how the mechanics of the werewolf gameplay work. It sounds stupid but Link pulled it off well.
Anyway, we will probably find out all this at E3.