I tried CentOS 8 almost immediately after its release, as it is one of the systems I have been using for years, on servers, workstations, and desktops.
The new CentOS 8.0.1905 operating system is now available in two different ISOs: the well-known CentOS Linux, the traditional, stable operating system based on RHEL, and CentOS Stream. The new CentOS Stream, according to the developers, is described as a platform that is between the Fedora and RHEL distributions.
However, since the last minor releases of RHEL before version 8, the company stopped supporting the beloved KDE Plasma desktop environment. Thus, the new CentOS 8.0.1905 was released with only Gnome as the sole desktop environment.
Below we will see how you can install KDE Plasma version 5.15.5, before it is released in the official CentOS 8 repos.
I should mention that so far the KDE desktop environment is running without any particular problem, except for one error that occurs occasionally. The error refers to kdeinit5, a Launcher for applications that require kdeinit support. 
But let's move on to the installation:
First we need to add the necessary repos.
If you don't have it installed, add 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 in EPEL8):
dnf config-manager --enable epel-playground
Then activate PowerTools
dnf config-manager --enable PowerTools
Now we are ready to move on to installing KDE Plasma
Let's clean up a bit
dnf clean all
and
dnf update
Run the following commands as root:
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 although 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 missing from the above installation are: calligra (an office suite)
with an error — too many dependencies,
telepathy, and python2-dbus, which is 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, don't forget to change desktop from Gnome to KDE.
