I don't see any good reasons to throw it away. Wayland, QML -- that all look rubbish to me.
kdm had no maintainer to port it to Plasma 5. Please add the information why other display managers are not sufficient.
1. KDM has better UI; 2. KDM is configured inside KDE; 3. It is old -- no need to learn new tool; 4. KDM is stable. LXDM autologin is broken, CTRL + Alt + Backspace is broken. SDDM is broken, doesn't start at all. I mean this is my local setup, but those products are not well.
Feel free to step up as maintainer if you think the product is worth maintaining.
So why you closing it if you asking someone to be a maintainer? They will not find your message if the bug is closed.
This is not a support forum. If SDDM doesn't work for you, file a bug against SDDM so the issue can be fixed but we are not interested in maintaining KDM. I am asking *you* to be the maintainer, you filed the bug, you know about it, so nobody else needs to be bothered with this.
That's strange how you developers easily judge about nobody or everybody. Everybody is silent. They just dump your product and go to something else or tolerate inconvenience. Only less than 1% gives feedback. If there will be request to have KDM maintained sooner or later there will be response. So please obtain a new maintainer! Why you asking exactly me if there is more appropriate person for that?