Cronie is moving to Factory, After testing update process, I found that best way how to switch to cronie as a default cron in openSUSE is simple move all cronie sources and patches to old cron package. so we will jump from (old) cron-4.1 to new cron-1.4.4 (which is cronie) and we don't need to use various hacks then (switching from cron to cronie is not update)
I already do this with cron in Base:System and I also created sr against openSUSE:Factory
If you have already cronie installed just remove it zypper rm cronie
If you hit some issues please file a bug report.