Not to mention that if keeping Sora on the eShop indefinitely is something that Disney won't allow, Sakurai would probably be more okay with a Sora Mii Costume eventually being pulled from the eShop by Disney compared to a full-on character.
"oh man getting Sora's likeness for a character is too hard and expensive let's still go though all that effort for a Mii Costume"Sakurai doesn't really seem to be on the same wavelength as fans when it comes to Mii costumes - for him they're a good consolation for fighters who didn't "make the cut," whereas for fans they're the end of the world and completely destroy a character's chances at getting into the game.
I can see him requesting Sora and "settling" for a Mii costume if the deal to get him as a character was too expensive.
I would rather have nothing