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360 video streaming presents unique challenges in bandwidth efficiency and motion-to-photon (MTP) latency, particularly for live multi-user scenarios. While viewport prediction (VP) has emerged as the dominant solution, its effectiveness in live streaming is limited by training data scarcity and the unpredictability of live content. We present 360LIVECAST, the first practical multicast framework for live 360 video that eliminates the need for VP through two key innovations: (1) a novel viewport hull representation that combines current viewports with marginal regions, enabling local frame synthesis while reducing bandwidth by 60% compared to full panorama transmission, and (2) an viewport-specific hierarchical multicast framework leveraging edge computing to handle viewer dynamics while maintaining sub-25ms MTP latency. Extensive evaluation using real-world network traces and viewing trajectories demonstrates that 360LIVECAST achieves 26.9% lower latency than VP-based approaches while maintaining superior scalability.