Description of problem: Support PackageKit so that user can switchover from yum to dnf as a backend. Nearly all other package managers support this including apt, smart, portage etc.
This is up to PackageKit (or whatever is going to supersede it) to implement the support for DNF. It is still unclear though if the PacakgeKit maintainers are even going to go for DNF or just use hawkey et al. directly. All in all, the future of this issue is quite vague and so I'm closing this bug.