"Killing" the service in the sense of minting new ones is no big deal and hardly merits mention.
Killing the existing ones is much more of a jerk move. Particularly so since Google is still keeping it around in some form for internal use by their own apps.
Don't they use https://g.co now? Or are there still new internal goo.gl links created?
Edit: Google is using a g.co link on the "Your device is booting another OS" screen that appears when booting up my Pixel running GrapheneOS. Will be awkward when they kill that service and the hard coded link in the phones bios is just dead
Google Maps creates "maps.app.goo.gl" links; I don't know if there are others, they called Maps out specifically in their message.
Possibly those other ones are just using the domain name and the underlying service is totally different, not sure.