Hi Env&Stack team,
I do not know if it is valid for our ML but I guess yes.
It seems that since Fedora 23 fedup is not going to be used anymore .
Instead of them new DNF plugin will be used. 
I would like to kindly ask you if we have something to add here.
And of course GUI is missing in Fedora for upgrades.
Zero downtime update is great idea. My last update from F21 -> F22 took
around 3 hours.
How it should work from Will Woods point of view:
So! For F23, fedup needs to be redesigned. Here's how it should work:
1) Download packages for the new system
2) Use the systemd Offline Updates facility to install packages
Red Hat, Inc