I think the biggest potential is with Microsoft Teams in business. It is ubiquitousness in people's work life, has access to data and has integrated with everything. And adding cortana to calls would be an easy step for people to understand and learn. People would say "cortana share my screen". People would learn phrases from each other.
But teams hasn't figured out how to send text in a coherent way.
It's used because companies can cheap out on buying a license for other communication applications, it is fundamentally worse than anything else in any other metric. If voice lets me respond to a message without hunting for the hidden reply because Teams shoves it below the bottom of the screen then it could be a win.
Considering UX is so low for Teams I doubt it will.
