I hope this is true...but I hope that it is for the Wii.
Personally, I am now hoping that since Metroid Prime 3 is single player, that Retro will do the Valve thing and be releasing a stand alone game with Metroid Prime 3 which is a Hunters Wii with online play. The game will be designed from the ground up to be a multiplayer FPS in the Metroid universe, but not restricted to Metroid rules.
I know that it will never happen and it is a silly dream of mine...but I still hope its true.