This doesn't actually work in the rules does it? The game cannot track what becomes of a spell once it resolves.

Effects that explicitly refer to cards after a single zone change can track those e. g. "When enchanted land dies, return that card to its owner’s hand." (Corrupted Zendikon).

More significantly: Eight-and-a-Half-Tails's second ability has he following ruling: "A permanent spell that becomes white this way will enter the battlefield and continue to be white until end of turn."