I tried CentOS 8 almost immediately after its release, as it's one of the systems I've been using for years on servers, workstations, and desktops.
The new CentOS 8.0.1905 functionality is now available in two different ISOs: the well-known CentOS Linux, the traditional, stable RHEL-based operating system, and the CentOS Stream. The new developer CentOS Stream is described as a platform between Fedora and RHEL distribution.
But since the last minor versions of RHEL before version 8, the company has stopped supporting the much-loved interface KDE Plasma. So the new CentOS 8.0.1905 was released only with Gnome as a unique desktop environment.
Below we will show you how to install KDE Plasma on 5.15.5 before releasing the official CentOS 8 repos.
Let me mention that so far the KDE desktop environment runs without any problems, except for an occasional bug. The error refers to kdeinit5 a Launcher for applications that need kdeinit support. 
But let's move on installation:
First we need to add the necessary repos.
If you have not installed it, add the epel-release with the following command as root:
rpm -Uvh https://dl.fedoraproject.org/pub/epel/epel-release-latest-8.noarch.rpm
and then enable epel-playground (Yes we will install it from EPEL8 playground until we see it at EPEL8):
dnf config-manager --enable epel-playground
Then turn on PowerTools
dnf config-manager --enable PowerTools
Now we are ready to move on to installing KDE Plasma
Let's clean up a little
dnf clean all
and
dnf update
Run as root the following commands:
dnf group install "KDE Plasma Workspaces"
dnf group install kde-desktop
dnf group install kde-apps
dnf group install kde-media - skip-broken
dnf group install kde-software-development
dnf group install kf5-software-development
Then we can add sddm as a desktop manager if we want though gdm works fine. Run the commands:
dnf install switchdesk system-Switch-displaymanager
switchdesk kde
system-switch-displaymanager sddm
systemctl set-default graphical.target
The packages that do not exist in the above installation are: calligra (an office suite)
by mistake - too many dependencies,
telepathy and python2-dbus, not used by RHEL8.
But with the above commands you will install KDE on your system before it is officially released, whenever it is released.
Tip: If you install sddm and see the login screen, do not forget to switch deskop from Gnome to KDE.
