Peter Robinson of Red Hat that's a contributor to Fedora and works on some ARM matters, shared that for Fedora 21, "the aarch64 userspace, while still not 100% there, is looking EXTREMELY good and there’s a number of people that are now putting it through it’s paces on a daily basis which in turn allows us to improve it as we go...we now have support for a number of hardware options to run the userspace. Some of them are emulated (qemu, ARM foundation model) and some actual physical (APM Mustang, AMD Seattle) if you’re lucky enough to have access. The support for these devices is improving all the time and support for kernel features are coming along pretty think and fast. So in summary the Fedora aarch64 is in very good shape for the Fedora 21 Alpha and will only improve as we apply polish along side x86 and ARMv7 in the lead up to Fedora 21 GA."
For those interested, Robinson shared this Fedora 21 64-bit ARM status update on his personal blog. With Fedora 21 not being due out now until November, hopefully by the time the release ships we'll have some Linux-friendly ARM64 hardware widely available.