I haven't really put my two cents in yet. I really don't know what ultimately led to the Dreamcast's demise, nor do I know how SEGA could screw their own character so bad.
Personally, I loved SA:DX and SA2:B. I bought them both for the Gamecube and they rea\main a couple of my favorite games ever. Sonic Heroes... meh. Didn't despise it, didn't love it. Shadow the Hedgehog I was not a fan of. But judging from popular opinion, Sonic 2006 really bit big wind. Having never played (for I don't really care to get a 360 or PS3) the game, I'm sure that I probably would've ended up liking it at least a little bit, seeing as that seems to be my opinions on 3D sonic games. And for the record, I'll agree that there are a couple characters that need to be axed, and FAST. The ones that bother me most are Silver the Hedgehog and Satan... err... Cream the Rabbit and her little chao. I don't have a problem with Shadow, honestly, I thought he was awesome in SA2B. And Tails, Knuckles, and Amy are all pretty much classic.
BUT, like everyone else here, I am worried about how SEGA will handle Sonic in Brawl, if he is in at all (which he better **** well be). I just hope SEGA realizes that they really have nothing to lose by doing it and finally just let Sakurai and his team put him in. And seeing as the people in SONIC TEAM won't be working on Brawl, I think Sonic is in capable hands. Sakurai is a good man and a very talented game maker, I for one have full confidence that he could do a great job with Sonic.