Red Hat doesn't have any btrfs engineers, they all moved to Facebook -- so they don't currently have anyone in-house to do btrfs work. SUSE does (one of the upstream maintainers is a SUSE guy). Facebook also runs btrfs.
Red Hat's plan for "replacing" btrfs is to write a bunch of additional tools around devicemapper/LVM. My experience with using LVM is that this is not going to end well -- if you thought btrfs was unstable you've seen nothing yet.
To be clear, btrfs does have its issues, but linking to RHEL no longer supporting something they never actually fully supported is a bit of weird thing to argue is a negative of btrfs. Red Hat doesn't get to by the sole arbiter of what is and isn't good software (and it should be noted that Project Atomic's snapshotting using ostree is simply not as good as using btrfs and the transactional-update integration into openSUSE Kubic -- btrfs snapshots are atomic for a start and rollbacks are a single syscall away).
