They seem to be claiming that the 'identifiable' data will only appear in a 'bridging' database:
"Your date of birth, full postcode, NHS Number and gender rather than your name will be used to link your records in a secure system, managed by the HSCIC. Once this information has been linked, a new record will be created. This new record will not contain information that identifies you."
So the stuff that is offered on the open market will be 'less' identifiable. (The black market is another matter...)