Santa was kind enough to bring my daughter Karaoke Revolution, and we've been having a ball with it. But, the microphone looks like it belongs to a 70's cassette recorder. (It's the same style as the Mario Party mics, just black.)
I saw that Konami made a pretty nice looking mic for the PS2, but after Googling the crap out of it I couldn't come up with anything else for the Gamecube.
He hasn't lent his voice for play-by-play commentary for a few years now and they didn't change the name then. Like you said, the Madden name is very successful brand and there is no reason to change it in the near future.