Meta's recent Muse family launches, including Spark 1.3 in early September 2026 and the open-weight Glimmer in August, have shifted focus to the next flagship iteration, internally referenced as Watermelon in leaked communications. This multimodal model is positioned as a GPT-6-class competitor with advanced reasoning across text, image, audio, and video. Trader sentiment reflects substantial uncertainty, with "Other" and numerous placeholders dominating at 50% implied probability amid unclear official timelines or naming conventions. Among concrete options, Muse Watermelon leads at 16.5%, ahead of thematic alternatives like Fire, Flame, or Nova, as Meta balances its pivot toward closed API models while maintaining developer engagement through open releases. No confirmed release window exists beyond projections into 2027, leaving room for shifts based on competitive benchmarks or internal strategy.