Does it mean it will be KDE 5.*?

What is the plasma version? What's its relationship with the KDE version?

Thanks for answering the noob question. I can never understand them though.

Plasma (Desktop) is the workspace. Plasma 5 is the newest version of the KDE Plasma workspace.

"KDE" is used for the community behind KDE software, much like e.g. Mozilla, Microsoft, Google, Apple, etc. It used to stand for "K Desktop Environment" and be this fuzzy term describing the workspace and a bunch of applications that came with it. This changed in 2009 for various reasons, but people still use it when they actually mean Plasma.

Thus, there is no "KDE 5.*" because we don't keep track of the version of our community.
Instead we have:

KDE Frameworks 5 - The new libraries and frameworks that KDE software is built on. Previously called KDE Platform.
KDE Plasma Workspaces - Workspaces created by KDE. The most common one is the desktop workspace (Plasma Desktop), but there could be others, like Plasma Netbook. Plasma 5 is the new major version of Plasma Workspaces built on Frameworks 5.
KDE Applications - Simple, applications created by KDE. Note that they don't have to run in a "KDE environment", you can perfectly run them in other desktops and even other operating systems than Linux!
KDE Software - General term for any software created by KDE.

And finally, KDE - You! And me. And everyone else in the KDE community!

You may also have heard of "KDE Software Compilation", which was used to describe the collection of software that was regularly released together (so instead of "KDE 4.8 released", it would be "KDE Software Compilation 4.8 released"). This term has been retired and for the 5 series KDE Frameworks, Plasma, and Applications have different release schedules.

Thanks a lot for the answer.