One Piece Speculation: Have We Seen Kaido Already?

So now that the Strawhats and Law's next aim is clear I'm going to present to you some of the speculation that we've actually seen "King of Beasts" Kaido already. Oda has done a lot of Color Spreads which show a lot of differenct characters and there are some that are unrecognizable.

 There's this color spread "New Age" that was released in chapter 693, in the color spread we may be seeing some of the main characters of this part of the story. In the middle we've got the alliance between the Strawhats and Heart pirates along with Momonosuke and Kinemon. Starting from upper left corner we've got unknown silhouette which may be Kaido, then Basil Hawkins, Blackbeard, Killer, Shanks, Eustass Kidd, possibly Big Mam, Scratchman Apoo, Aokiji Kuzan, Doflamingo Donquixote, Akainu and Jinbe (Jimbei).

Doflamingo is the only Shichibukai in the picture and the characters seem to be somewhat randomly selected, so it could be a hint of who are being focused on the arcs to come. (Aokiji) Kuzan in the picture strengthens this theory since he appeared only 5 chapters after the release of this color spread.

I played around with the color spread picture and made this to make it a bit clearer what Kaido could look like. Based on that I'd say that his Zoan could be something like a Lion:
  "A common depiction is their representation as "king of the jungle" or "king of beasts"; hence, the lion has been a popular symbol of royalty and stateliness" - Wikipedia article of Lion.
Look at the ears, those definitely don't look like humans and the skin of the character seem to have some kind of stripes or something like that so based on this I wouldn't say it's impossible of Kaido to have Neko-Neko No Mi: Model Lion. He would just be so incredibly powerful otherwise to compensate with his lack of incredible Devil Fruit power.

The character however also resembles a little bit of Jean Bart, but that wouldn't make much sense.

By the way, if someone has incredible drawing skills and would be interested in drawing "missing parts" for that picture of "Kaido" I would very much love to see that.

This one's a very old one, but I think it still deserves a mention.

This is some very old color picture which Oda made which includes Buggy, Shanks and lots of unknown characters. Now look at the background and you may see that the person there looks very much like Kaidos silhouette.

Basically the only thing that we've got is this Silhouette of Kaido in chapter 432, but as we know Big Mam didn't look anywhere like what she looks in the picture, so the real design may change dramatically. But I have to say that the person on the first picture resembles pretty much Kaido's silhouette. This is however a long shot and have been around for pretty long.