Lync will become Skype for Business officially on March 18th. Rebranding will bring a new modern UI with elements from Lync and Skype and it will include well known Skype icons for calling and call monitor, possibility of calling any Skype user on any device, etc.
“A new client experience, new server release, and updates to the service in Office 365.”
Users with on-premises Lync servers will have to upgrade Skype for Business manually. For Office 365 for business customers, it will be done automatically.