Microsoft is rolling out an updated version of Skype 8.0 for Windows desktop today, July 16, and will make this the replacement for Skype 7.0, aka the Classic version. After September 1, only Skype version 8.0 will work, officials said.
Update: Here's some clarification about which version(s) of Skype are available for Windows 10 users. From a spokesperson:
"Skype users on Windows 10 have two options. They can continue using the UWP app that comes installed with 1the latest version of Windows, a k a, 1803 (MJF: which is Skype Version 12, I believe). Or, they can install Skype version 8.0 by visiting www.skype.com/download and selecting "Get Skype for Windows' from the dropdown."
Skype 8.0 on Windows 7 and 8, which don't support UWP, is simply the latest version of Skype.
Microsoft is rolling out more Skype features across platforms over the coming months. Skype version 8.0 is rolling out on the iPad now. A "read receipts" option for Skype chat is on the docket, as is call recording (with automatic participant notification), group links and more, according to today's blog post.