It took a while, but Nintendo has responded to the mailed copy of VixenVotaries' Krystal artbook. If you were unaware, the artbook project was an effort started in April to gather various Krystal artists together to create new Krystal artwork, which would then be compiled into a book and sent to Nintendo with a note about how special Krystal is to her fans. They wanted to show their support for Krystal being made playable in Super Smash Bros by creating a physical, tangible work of love. Later, after the book was sent to Nintendo, the project was released to the public so all Krystal fans could print their own copy.
The letter that VixenVotaries received from Nintendo expresses delight at the devotion we Krystal fans have for our beloved blue vixen. They acknowledged both the individual effort and the passion of the whole Krystal fan community. Art projects and other fan works like this that Nintendo receives are shared around the office to be enjoyed by the employees, and the book may even show up at Nintendo events in the future. As for the request to make Krystal playable, Nintendo's representative, Adam Kuta promised to pass the sentiment along. No confirmation, but we weren't really expecting one.
All in all, a good effort by everyone and a happy ending for this project. Well, ending for now. We'll see what surprising the future holds.