- Edited
After a novel is completed, yes, the privilege chapters of that novel would become available to the non-privileged readers through the regular release schedule.
So, for example, if there are still 10 chapters left to the completion of a novel, and all of them are privilege chapters, once the author/translator set the novel's status to completed, those chapters will be released from the privilege pool to the normal readers through the regular release. If the regular release schedule is 2x daily, then normal readers will get to the end of the novel in 5 days.
Purchasing privilege is never mandatory for reading a novel until it's completed. But as I said, you'll still have to unlock the chapters with coins or fast passes once they're released from the privilege pool.