cloudevents.js - looks alive and well. Points to v1.0.2 of CE
CloudEvents JSON Schema - last touched 2000, and it talks about v1.0 so it's probably ok. Leave it
Knative eventing - alive and well. Leave it
VMware Event Broker Appliance: looks alive and well. Leave it.
Wait for a response, if none, drop them
CloudEvents.NET only references v0.1 of the spec. I've opened an issue asking if they plan to upgrade to v1.x. If they don't answer (or say 'no') I recommend we drop them - project appears to be dead, no edits since 2018
URL: https://github.com/cloudevents/spec/blob/main/docs/open-source.md
I went thru the projects on there and grouped them based on my analysis:
Leave them
Wait for a response, if none, drop them
Drop them