The thing everyone has to remember is the website is still going to be updated long AFTER the game is out. Melee's site which was run similar to Brawls was still being updated by Sakurai, months after Melee was released in Japan. The other thing to remember is Sakurai has done double and sometime even triple updates. I'd imagine when we closer to the Japan launch we'll be seeing a lot more double updates every week. Hell, I wouldn't be surprised if the week of the Japanese launch every single day is a double update.
And in terms of a Megaton, I'd imagine we might get one this Monday or Tuesday. The fact that Christmas is celebrated in every country that's represented on Brawls website, makes it likely that he'll reveal something big as a Christmas present to the world. Plus next week marks the one month period before the Japanese release which makes something big likely as well.
Unlike America, in Japan Nintendo usually start hyping there games up at the one month period and every week they reveal more and more. Which means we will start seeing the rest of the starting lineup soon since Nintendo's commercials in Japan usually start around the 2-3 week time period before launch. And since the biggest selling point to a game like Smash Bros is it's playable characters, they will show all the starters in the commercials since that's what's going to create the most hype.
Here's what
Melee's Japanese commercials were like. Chances are Brawls will be similar which means all starters should be shown in them as well.