I'm posting here my thoughts on the whole box theory debate:
I don't buy it for several reasons. People immediately assumed that the artist, who has to be an external to Nintendo, who made this box-art knows the final roster, or at least the number of fighters. But what if that isn't the case? It would make sense to not tell anyone extern such a precious information, since it is preventing a possible leak. So let's think it in another way: why were the characters placed in that order?
Considering that Isabelle is missing, the graphic artist had 69 (if Mii Fighters and Pokémon Trainer are counted as 1) to place. As you all know 69 isn't an even number, so in order to split them between two sides he had to create either 70 or 72 spaces.
Now if he went with the easier 70, that would have meant 35 characters for side, which would result into a 5×7 or a 7×5 template, which no matter how you arrange, it doesn't look too good since it squishes the boxes, making them slim and tall. But with 72 spaces we have a clean 6x6 template, much cleaner to the eye. Let's not forget that the job of a graphic artist is to make something appealing rather than something that makes sense or is functional.
Now what about those empty spaces? With 69 characters that means that we have 3 empty slots, but leaving all 3 on a single side probably doesn't look too good since it is half a row, so he splitted between the two sides, one on a side and two on the other.
For the way the characters were added it seems to be just a "9 here, then the next 9 there" pattern, very easy and that mixes them better than just do "first 36 on a side then the rest on the other".
And that's about it. He made this template just because it looked nice, but due to a coincidence the blanck spot on the other side can be fit with a heavely rumored character (rumor started by the only reliable leaker who is currently expectung 3 more characters, but I digress), but if this artist really knows about Ken in order to leave a spot for him then he is informed about the whole roster, and that's before Isabelle was even revealed! It would be a huge risk for leaks, and we know they want to avoid them at all cost. Not even all the employee at the Threehouse can even SEE the game, in fact the main NoA reps who talk about Ultimate are Nate and Bill, two of the higher ups at NoA. I really doubt they would let the entire roster in the hands of an external graphic designer...especially if they don't even hand him the Isabelle artwork.
Thinking about it, it is similar to the European LE, which features the "Everyone is Here!" artwork. It was revealed shortly after the Smash direct in August, but it already featured the updated artwork with Simon, Richter etc etc. Considering this I wouldn't exclude that the American LE was made during/before August like the European, and that would also explain the total lack of Isabelle in it. Why would they have held off the announcment? They waited to reveal the Smash Pro Controller separately, and then waited for the next Direct, just like how the European LE was announced after a Direct.
And if it was really made in August that makes even less likely that they would have revealed the roster to an extern artist.
Also we shouldn't forget that this is clearly a Work in Progress since it lack Isabelle, if more than two characters are revealed then we can see those icons resized and rearanged in order to accomodated them, and they might even fill the empty slots with the game logo if they so decide. And all of this is completely ignores the back of the box, which might even have more characters. It might even feature the Original 8 there because that is the starting roster for all we know.
In the end I don't belive this theory, it just feels like people looking at the website slots i order to predict how many fighter we will see, and we know what those type of reasoning brought us. "Wolf is surely DLC" or "There have to be 5 more characters in Smash 3DS" are just the first examples that come inti my mind. And the worse part is that we are basing this off a box made by an external source instead of Nintendo's official site.
Also it doesn't make sense ti remain with just 2 more characters, one of which is an echo, to announce right before release, when in August you revealed 5. Heck, what would be the reason to end witn Ken and Inceneroar over Simon, Richer, KKR etc etc? None of them are particularly requested or popular, and none of them comes from the Ballot. Ending just with them seems like a very bad marketing choices. And Sakurai, someone who even explained during E3 how to keep the pacing if a video going strong in one of his columns, knows that this would be a quiet ending the the huge hype cycle of this game.
It's also uncharacteristic of him to do something like this. He usually reveals last the characters that, while might not be super popular or requested, bring some very unique movesets and mechanics to the game. Brawl ended with Olimar and his Pikmin moveset based around managing them and Smash For with Shulk and his Monado arts. I just can't see an echo and Inceneroar, who while unique lacks this kind of extra flavour, filling this role.
