George Harrison's "Long Long Long" could easily fit on his first solo album All Things Must Pass (1970). Its delicate and spiritual character is very similar to "My Sweet Lord", "Hear Me Lord", or the album's title track. Likewise, although the album version of "While My Guitar Gently Weeps" is heavy, the first take of the song was very lite, and equally anticipatory of All Things Must Pass.
Although written by John Lennon, "Good Night" is sung by Ringo, and would not be out of place on his first solo album, Sentimental Journey (1970), which is a compilation of old song standards that Starr grew up listening to. While "Good Night" was written in 1968, it is in the same 1940's style as the tracks on Sentimental Journey. The one song on The White Album actually written by Ringo, "Don't Pass Me By", would similarly fit on his second solo album, Beaucoups of Blues (1970), which features country & western music. In fact, the track "I'd Be Talking All The Time" off Beaucoups of Blues features the lyrics, "For ev'ry dream that came my way, A million passed me by."
John Lennon's oedipally confessional "Julia", which closes disc 1 of The White Album, would fit perfectly on his first solo album, John Lennon/Plastic Ono Band (1970), which features similarly poignant tracks such as "Mother", "My Mummy's Dead", and "Look at Me" (which also uses the same fingerpicking style as "Julia"). And although ultimately left off The White Album, Lennon also wrote "Child of Nature" around the same time as "Julia". The song was re-worked and released on his second solo album, Imagine (1971).
Paul McCartney's White Album tracks do not fit quite so nicely into the foreshadowing category of the other three's songs. It is difficult, for example, to imagine "Helter Skelter", "Back in the USSR", or "Rocky Raccoon" on his first solo album, McCartney (1970). In his book Tell Me Why, Time Riley suggests that " 'Ob-La-Di, Ob-La-Da' could have appeared on McCartney's Ram" (page 288), but I apparently don't find that match as strong as he does. McCartney's "Junk", however, much like Lennon's "Child of Nature", was originally considered for inclusion on The White Album, but ultimately left off. The song would be included on McCartney. Similarly, "Teddy Boy" was written at the same time (while in India), but considered for and ultimately left off the Let it Be project, to be revived and included on McCartney.
Cott, Jonathan and Christine Doudna, editors. The Ballad of John and Yoko. Rolling Stone Press, Dolphin Books, DoubleDay & Company, New York, NY, 1982.
Riley, Tim. Tell Me Why: The Beatles: Album by Album, Song by Song, The Sixties and After. Vintage Books, a Division of Random House, Inc., New York, NY, 1989.