Earlier quoted context omitted.
You never know. This is what they said about schemas too not many years back.
Have there been any discussions whatsoever about adding some sort of namespacing mechanism to JSON?
It's for making interoperable APIs, so there is a good motivation for namespaces. But the namespaces are much less intrusive than XML namespaces. Ordinary API consumers don't even have to see them.
One of the key design goals of JSON-LD was that -- unlike its dismal ancestor, RDF/XML -- it should produce APIs that people actually want to use.