Assumption: Whatever schemas our WG comes up with for resources, they will need to be locally extensible.
...I'd also like to expose a JSON-LD representation of my resources. JSON-LD is fine with multiple vocabularies and you can in fact 'ignore' properties by not defining them in the @context. This means this is my source (note that I shortened the polygon value for readability):
From a Linked Data and JSON-LD point of view this is completely correct. The properties ID, MUNICIPALITY and WATER aren't mapped in the @context so the parsers ignore this.