There's been no recent pushes for making Btrfs the default file-system of Fedora Linux while many releases/years ago there was once talk and hope of it becoming the first tier-one Linux distribution using it by default rather than EXT4/XFS. However, after years of development, Btrfs isn't the default on Fedora -- but those customizing their install can continue to setup a root Btrfs file-system. Other Linux distributions like openSUSE and Mageia have since defaulted to Btrfs, but Fedora apparently doesn't feel ready yet to make this jump.
Btrfs as the default for Fedora 23 was brought up today on the Fedora devel list. However, the consensus at this point seems that it will not be a pursued change for this Fedora Linux update due out before the end of 2015. Fedora continues to use EXT4 as the default on the desktop while Fedora Server with Fedora 22 transitioned to XFS by default.
Perhaps in 2016 we'll see Fedora pursue Btrfs by default given the vision of systemd developers that does involve Btrfs functionality, etc.