You know, with Captain Falcon also being shown along with Robin and Lucina, does anyone else get the feeling Sakurai is going to show all the characters before the games release? We already had 2 Fire Emblem characters shown before today, and Sakurai had no problem leaving Captain Falcon hidden in Brawl. Robin and Lucina (even if an alt for Marth), could have been some kind of unlockable to get in the game as well. Revealing all this information now when he doesn't have to show this much, kind of points to that.
As we all know from his trolling, Sakurai understand the internet and message boards really well. I'm sure he saw with Brawl how some stores in Japan broke the street date and released it a few days early and less then 24 hours later, the entire roster with pictures and movies of them were all over the internet. I wouldn't be surprised if this time he's like "**** It", the entire internet is going to get the roster spoiled for them days before release anyway, so he wants to be the one to do all the spoiling this time.
I mean before today, we only got new reveals during Nintendo Directs. Well know that Sakurai has no problem revealing new characters and trailer on the main site without a Nintendo Direct, who's to say he doesn't have a few more of events like today planned in the next few months?