Again, thanks goes to CyClone for locating this. The intrepid reporters at planetgamecube.com interviewed Yugi Naka at E3. All references to Nights and Sonic are vague, as usual, but there might be hope that Sonic will come to Gamecube.
Max Lake: I was wondering if there is any chance we’d see a Sonic game on the GameCube in the future?
Naka-san: (smiling) I have to ask Sonic which hardware he wants to run on.
…
Max Lake: Is there any chance we’ll see any new Nights games in the future?
Naka-san: A lot of people tell me that! I haven’t even made it for the Dreamcast, so we’ll have to see.