Microsoft is quietly replacing OpenAI and Anthropic models inside GitHub Copilot, Excel and Outlook, and CEO Satya Nadella just explained the plan

Microsoft has started routing work inside its own products away from OpenAI and Anthropic, and towards models it built itself. Satya Nadella laid out the reasoning in a long post on X, describing a system where Microsoft’s in-house MAI models take over tasks once handled by frontier models from its partners. GitHub Copilot, Excel and Outlook are already showing what he called promising early results. Copilot Chat and PowerPoint are next in line.

The logic is cost. Nadella’s framing is that software now has a real marginal cost for the first time, which makes the choice of model a business decision rather than a technical default.