Elon Musk's September 14, 2026 X posts outlined xAI's (now operating as SpaceXAI/SpaceXSI) iterative roadmap, positioning Grok 4.8—a 2.5-trillion-parameter model on a new C++ stack—as the next step after Grok 4.7's September 21 release, followed by 4.9 and then Grok 5 as the version expected to reach or surpass AGI-level performance. Training continues on Colossus II with Nvidia hardware and SpaceX engineering data integration, which analysts like Gene Munster highlight for potential engineering-task advantages. Earlier 2026 release windows have slipped without official confirmation, leaving no firm Grok 5 date while interim models ship steadily. Key near-term signals include 4.8 reinforcement learning progress, multimodal fixes, and any benchmark comparisons against competitors like Anthropic's Opus or OpenAI models.