He assumed that Google assured him that his current data would be safe. But saying that your account will move into read only mode doesn't equate to keeping those much TBs of data on server forever.

Though I have a question. Was this unlimited service that Google offered was a one time payment thing(seems unlikely, since only couple of cloud providers like pCloud do so and that too on a much lesser scale) or a recurring subscription thing? If it was the later, then it is naive to believe that a for profit corporation would keep that much data without raking in money.