When Your Rival Becomes Your Engine — March 17, 2026 Three stories about how the AI platform wars are collapsing traditional competitive boundaries — and what it means for the companies running on these platforms. Stories Covered: 1. Microsoft Copilot Cowork / Anthropic Partnership — Microsoft launched Copilot Cowork built on Anthropic's Claude technology, bundling it into a new $99/user Frontier Suite. Copilot paid seats are growing 160% year over year, and 90% of the Fortune 500 now use Copilot. Sources: Axios (https://www.axios.com/2026/03/09/microsoft-copilot-cowork-anthropic), Microsoft Blog (https://www.microsoft.com/en-us/microsoft-365/blog/2026/03/09/powering-frontier-transformation-with-copilot-and-agents/) 2. Claude Marketplace Launch — Anthropic launched an enterprise app store where third-party tool spend counts against existing commi ...