Sega probably won't, despite the fact that it would be cool. There are several reasons:
-Sonic 2006 was developed with graphics in mind. It is one of its main selling points, apparantly.
-The Wii wasn't designed with regular gaming in mind, really.
-Because of the fact that Graphics is the focus, and the Xbox 360 has bigass processors or something, thus giving it a speed boost, 2006 would not run well on a wii if it was ported. Loading times would be ultra-atrocious, and the framerate would have to be toned down.
-Doing the above would probably ask for a full rewrite of the game.
-Secret Rings is already promising something fun to all Sonic fans that sided with Nintendo after the death of the Dreamcast.
-Sega doesn't want to look ultra-friendly with JUST Nintendo anymore. They've already given their apologies to Nintendo (sonic advance, rush, sonic adventure ports, etc.). They're a third party, and they want to establish that to their nintendo fans (unless they get REALLY bad business otherwise)
-I'm not sure about this, but I don't think downloadable content is available on the Wii.
-What would the new features be on the wii? It's debatable as to whether the game would have to be redone or not.
And, sadly, several other reasons, too, but I'm too lazy to write them.