Lync did what it supposed to do but was not widely used, infact the mobile version of the software was not a very good instant messenger at all. There were constant delays when communicating from mobile device, however the desktop version did the job well.
So where does Skype fit in? The main reason that Skype was purchased was because of its dominance in the IM market and it was and still is the preferred video chat software around the world.
Recently Microsoft announced that it will do away with its Lync software and port all users to Sype For Business. This will give Lync users the same look and feel of Skype along with the mobility and quality of IM and video chat services that normal Skype currently offers.
Network admins also have the option of opening Skype For Business to normal Skype users so you can chat to friends and family as well as stakeholders from other companies who sit in different domains.
This is going to be widely accepted by corporates as they have already started embracing social media as a great marketing tool. The launch is said to happen soon so look out for it!