I've said it before and I'll say it again - my box skepticism has nothing to do with characters. I'm not expecting that 'extra characters' will suddenly get Dovahkiin playable.
My one question with this is why Ken has to be the one to fill out the box. He could, but I think it's equally likely that they left that extra space blank next to Cloud (or before Shulk). That would put the empty space at the bottom back corner of the box - which as soon as Isabelle is put in, would make the two sides match with the bottom back corners blank. What is my evidence? None...except that's precisely what the card did, when it put a blank before Ryu to match the blank after Isabelle.
Ken is probably still in because of Vergy/the picture. I don't think because of the box. Correlation does not imply causation.
Because the Ken argument is not a look at the box theory on its own, its looking at the box theory and Vergeben theory in tangent. If Ken is in (and he's very likely to be in) he has to show up next to Ryu in that box for their pattern to work. There's nothing directly part of the box theory that suggest Ken, only indirectly.
But taking all the factors into account, either Ken is in and we're probably getting two more characters, or Ken isn't in and we might get quite a few more.
Or Ken is in and just not on the box for some reason.
Or the box is really just a place holder despite its specific pattern and we've got 10 more on the way and they're all gonna be on the box.
Or the box was an illusion all along, there never was a Smash Ultimate, wake up Neo.