it's long past time for Fedora to support ARM, and several other architectures.
unfortunately it's more than just pointing a cross-compiler at your tree and letting it churn for a while. Debian has been doing the work, and a lot of testing. RedHat will now need to start doing this.
I also wonder how well it's going to work to base a phone distro (which may not be upgraded entirely for years) on a distro that only has a 12-month support window.
I've built small system images from both RedHat and Debian distros. It's _much_ easier to strip down the debian distro. The OLPC software fiasco had many causes, but I think that one of them was the problem of trying to balance between forking packages and living with the bloat.
In this case I suspect that after a year or so all that 'based on Fedora' will mean is that it uses rpm packages, but the software itself will probably have very little in common with the then-current Fedora distro.