Battle of the personal digital assistants

Battle of the personal digital assistants?
With so much talk about AI going awry, perhaps we should think more of what is already around the corner. Very soon, if not already, our personal digital assistants will become ubiquitous and do all sorts of our administrative chores. One such, making appointments would be very handy indeed.
 
Finding an agreeable time-slot to meet other busy people can take quite a few emails back and forth. But what is the alternative unless the calendar is in the public domain, something most people will never want?
 
Perhaps we will see the battle of the personal digital assistants. You will simply ask your digital assistant to find a time that fulfils some specified criteria, such as before date so and so, or a time when you are already in the area, but not too close to a high-priority presentation or meeting. Already, most of the available information to such trade-offs in time and place are already available and easy to input. The next step would be a minor one in delegating to two digital assistants to sort it out.
 
So we will have digital assistants talking to each other in long loops. For sure, there is scope for interesting errors, both innocuous or serious. On the more light-hearted side, I wonder how Cortana will get along with Siri or with Alexa? Will we be better served by two different digital assistants that represents their clients faithfully without conflict of interest? Will there be a bias if Siri talks to Siri, based on some commercial algorithm? Perhaps a new area for the competition authorities to concern themselves with!