I don't know if the retail industry invented the term omnichannel but it was the first place I can remember hearing the term. The term was intended to capture the fact that, until then, you could deal with a single brand that had both brick-and-mortar and online stores, but the customer experience was as if they were two completely different business. Evolution of that industry, with the accompanied competition and attrition, have basically eliminated those types of inefficiencies.
The term omnichannel has also evolved, and today it is often used to indicate that an enterprise offers many different channels through which they can be contacted. Today businesses clearly need to support the channels their customers prefer, but we can't forget the other primary principles on which the retail definition was based: brand consistency and customer experience.
A digital-first omnichannel contact center world that incorporates a single customer user experience, across channels, while maintaining a comprehensive view of the customer and a consistent brand image, is inevitable. This is the field where the next great battle for Customer Experience will be fought. And just like Retail, the winners will be those who are able to recognize and embrace the shift.