At the end of the novel is Offred presented as being ultimately liberated?

Like Offred, the reader has learned to believe in multiple possibilities. It doesn't really matter whether or not Offred escaped. Her words escaped, so she survived. Though no one knows her real name, she is not like Ofglen; she has not been erased from the historical narrative. Whether or not the historians understand the importance of Offred's effort, the reader understands that she has made her story permanent, and has thus, in a way, given herself and her fellow Handmaids immortality.

Like Offred, the reader has learned to believe in multiple possibilities.