Dave Michels comes up with a new acronym for UC - workstream collaboration and communications, or WCC - but that doesn't change the fact that integration, implementation and training are required to put the comm pieces together with the collab pieces to make this stuff work for the workers in a fashion that they will use it.
In the enterprise, it is mainly a fight among Avaya, Microsoft and Cisco. In the SMB market, the consumerization of the IT space means that people want it to be as simple as their iPhone (Facetime) or Skype or Google. And they want it all at their fingertips.
Maybe UC should just be a screen from a smartphone to pop open WhatsApp, chompSMS, gmail, etc. All notifications in one place. Etc. ideally that is what people want, but it is a huge challenge to deliver anything like that.
It started as VoIP, became Hosted VoIP, then Hosted PBX, then Cloud Phone System, then cloud communications, UCaaS, UC, hosted UC. It pivoted to UC&C for unified comm & collab. All the names don't change the fact that the benefits and outcomes are lacking due to integration unless you go single supplier.