Microsoft Cortana now only 'soft-serve' on Windows 10 - CNET

In a blog post today, Microsoft aounced that it was removing the ability to deliver results from its Cortana voice-assistant from any search engine but its own Bing or browser but Edge on its Windows 10 operating system.

The move comes as a way of "protecting the Integrated Search Experience in Windows 10." Basically, Microsoft says it can't guarantee a good experience with any other combination of applications, so it's taking away the option.