They already do. It was NT Embedded back then and Windows Nano Server now. Believe me, they're aware of the value of that kernel. Also it's trivial to replace

They already do. It was NT Embedded back then and Windows Nano Server now. Believe me, they're aware of the value of that kernel. Also it's trivial to replace the UI. Minus the 5 billion dollars in R&D of course. But it's just one registry key if you want to get started on it...