Since the whole Megaton announcement, I refuse to listen to these rumours, especially from IGN.
Factor 5 are third party. They are a part of Lucasarts, but have a very good working relationship with Nintendo. They have made codecs for the Cube for video compression, and also made Rogue Squadron: Rogue Leader, a very good game too. They have a project in development, but no details have been released as yet.
Silicon Knights are a Nintendo second party. They were bought out somewhere around 2000, when Eternal Darkness showed great promise. I haven't heard any news of a new project, which most people are hoping is Too Human, a game that was shelved so Eternal Darkness could be the focus of the company.
Free Radical Design is a third party, owned by Eidos. There is little chance they will be bought out by someone, unless Sony or Microsoft are looking to shell out for one game every two to three years.
Star Fox: Armada as the mystery game? I reckon Nintendo will start to hype up F-Zero AC/GC before that happens.
My money is on news about the Mario Kart/Tennis/Golf franchises. Some screens or video to make us happy. These games are a given, its just a matter of when.