Depends on what you mean by cel shading. If you're talking about the way it was done in WW, then no, I seriously doubt Nintendo would do that because of all the complaints it got from a large percentage of fans. If it's some other style we've never seen, I guess it could be a bit more probable, but I'm still putting my money on the darker style graphics of TP. Those graphics kind of established that Zelda wasn't just another sell-out E game for the Wii, and I think it's the best way to stay on top of the likes of Sony and Microsoft.