Stretch to Buster with sysvinit

[Roger Lynn]

Hi,

I have three Stretch AMD64 systems with sysvinit - a desktop and laptop 
running KDE and a headless server. Is there any information available 
anywhere to tell me what will happen when I attempt to upgrade them to 
Buster? The release notes don't mention it and other sources I can find just 
talk about switching from systemd to sysvinit, which doesn't look easy with 
a desktop environment.

The KDE systems have systemd-shim installed, which is not present in Buster. 
Is this going to cause problems? Will the server be okay? Should I just stay 
with Stretch until Bullseye is released or consider moving to Devuan after 
more than 20 years with Debian?

Thanks,

Roger