Having been in the IoT and M2M space for 2-decades we believe that there a need to be a re-think over the Hypercat and the PAS 212 Draft Standard as we find the use of JSON rather heavy and inefficient on data transport, storage and manipulation.
JSON with its textural nature eases the process of human sifting of data, however as IoT is intended to be Machine to Machine (M2M) and Machine to Database one has to question the validity of its choice.
In the practical real IoT (M2M) world many data transport media such as Radio Telemetry and Satellite have and will always have very limited bandwidths where every byte counts, totally eliminating the notion of using JSON in the field. CSV is by far the most efficient and has another advantage that a Hacker would not necessarily have a clue as to what each field contains. Only the central relational database would have the answer.
In summary, PAS212 and the supporters of Hypercat do need to ensure that there is an understanding that the Internet is NOT everywhere and lean data is essential for low bandwidth systems and battery life.