In the Celestial Kingdom, will all people have white skin?
When the Father and the Son appeared to Joseph Smith, as written in Joseph Smith History, he did not describe the Father and Son as white, but he did describe them as such that their glory and brightness did defy all description.
When Joseph Smith was visited by the Angel Moroni, the only comparison we have to the color white is the robe which Moroni was wearing. When describing Moroni’s appearance Joseph again declared, vs. 31-32:
“Not only was his robe exceedingly white, but his whole person was glorious beyond description, and his countenance truly like lightning. The room was exceedingly light, but not so very bright as immediately around his person. When I first looked upon him, I was afraid; but the fear soon left me.”
Our purpose in coming to this life, as you already know, was to gain a body so that in the resurrection we would be as God is. I would assume, that our skin color will not matter, what will matter most, is the type of glory we obtain.