They HAVE to make this multiplayer - and online would be incredible. From the looks of the videos of IGN - the Solar Empire are in, and a country in blue (Britain?) who seem to be fighting the Western Frontier. Also, the graphics are definitely better than the GC original, and those videos are from 2006 so could have improved since then? It's also good that the game is using the pointer of the Wii remote instead of keeping the controls like the original.
What I hope is they combine the gameplay of the GC version with the extras from the GBA games (Map Room, Versus Matches, Map Maker etc).
Definitely a must for a fan of the GC or GBA games.