Yum Set To Be Retired In Fedora 29
DNF has advanced a great deal since its original introduction in Fedora 18 and then becoming the default in F22. DNF2 brought many improvements and this "Dandified Yum" continues doing great on Fedora 28.
The time has come to deprecate and remove Yum (v3) and related packages like yum-utils and yum-metadata-parser from the distribution. So there's now the feature plan to get Yum deprecated and removed, but first there are still a few stragglers depending upon the old Yum packages that instead need to be properly migrated to DNF.
Fedora 29 is shaping up to be a huge update with many changes and hopefully won't end up being like some of the bumpy Fedora Linux releases of the past given the many ambitious changes. Fedora 29 is currently scheduled to be released by the end of October.