Even though I know the epilogue hasn't come out, I still can't help but wonder what happens to the Alpha kids after Caliborn's masterpiece. John is in the Juju with the other Beta kids, so they can't recon back to Earth C. Is Caliborn's planet a long forgotten Earth B or C? Were the Beta kids released when Vriska used the Juju?

Caliborn’s Planet is BOTH Earth B and C. They’re the same planet, Earth C is just terraformed and moved from the B Universe to the C Universe. However, it is Earth C after millions of years, completely dried up, and absorbed into a SBURB Session, so like, it may as well be another planet entirely. LOCAM to be specific.

Whether the Beta Kids were released or not, depends on your reading of the Ending and what you think actually happened in the Rapture. Them being released is a possibility, if you take the Masterpiece as the Timeline we’re following at the End, with everyone ending free again and happy. Otherwise if you consider it another Timeline, the Alpha Kids ending up trapped in a Dead Session and the Betas being absorbed permanently into the Juju, which is then likely absorbed into the Black Hole with everything else, is definitely a possibility. It’s ambiguous on purpose.

At least until the Epilogue comes out, and even then, maybe still.