RHEL 8 hasn’t yet been released but is expected around S1 2019 (there should be a beta period 6 months before).
We already know some aspects of it:
- it will use the dnf command instead of yum with an almost identical syntax,
- the file system Btrfs, once in technical preview, will no longer be available,
- concerning the Python language used for most of the system scripts, the version 3.x will replace 2.7,
- about LDAP, OpenLDAP won’t be available, you will have to used the 389 LDAP server or something else,
- you won’t be able to remove NetworkManager from your configuration (it’s already the case with the Gnome graphical environment in RHEL 7.5).
We can expect some other things like:
- a new version of CGroups: cgroups are a way to assign resource limits to processes. CGroups V2 would bring a better interface,
- it shoud be based on the Fedora distribution as usual (perhaps Fedora 27 with LTS kernel 4.14),
- Firewalld should use nftables as backend.
According to a comment at the centosfaq.org website, if you do support calls to RH, one option for picking the OS version is now “RHEL8 alpha” (June 14, 2018).
Also, if we refer to a June 2018 bug report, the installation of RHEL 8 alpha is already working.