"Might he not care whether the NHS survives?" I don't think anyone could be so short-sighted as not to care whether the NHS survives. They might wish to make drastic changes to it, but letting it totally collapse without surviving would nor be in their interest.
Its total collapse would leave 150,273 doctors, 377,191 qualified nursing staff, 155,960 qualified scientific, therapeutic and technical staff and 37,078 managers unemployed, hundreds (thousands?) of hospitals without staff or funds, and millions without any healthcare at all.
That would hardly improve the chances of a government being re-elected, so would not be allowed to happen.