DisplayManagerRework: how to handle upgrades?

[Rex Dieter]

OK,  so we have  
https://fedoraproject.org/wiki/Features/DisplayManagerRework#How_To_Test

that tells one how to enable the display manager of your choice, via
systemctl enable --force xyzdm.service

But, how to handle upgrades? (or is this case already handled somehow?)

Off the top of my head, perhaps create some sort of scriptlet (probably to  
live in initscripts, since that's what owned prefdm) to parse 
/etc/sysconfig/desktop to make some educated guess about which dm service to 
enable.

thoughts?

-- rex