When it was first released, A Doll's House created some controversy through Nora's decision to leave her husband. The ending was changed to accommodate audience sensitivities and shock that Nora would actually leave her children. Ibsen himself was outraged that he was effectively forced to provide an alternate and seemingly more appropriate ending which he hoped would only be used in extreme instances.
Any modern readers or audience will obviously interpret the play in their own way. In my opinion, the ending provides hope because it enables both Nora and Torvald, both equally trapped within their social roles, to examine themselves and become better people. The difficulty may lie with Torvald who has not had the same revelation of his character as Nora. He saw her as "a hunted dove whom I have saved from the claws of the hawk" and until he recognizes his own contribution to her dependence on him and his own reliance on it, he will be unable to change.
By leaving, Nora is giving Torvald the opportunity to reflect on his own shortcomings. Nora is affected by the belief that she is perhaps not good enough for her children and may negatively influence them. Torvald has always maintained that the shortcomings of the parents are "in the blood" and she does not want to have any more effect on her children than she may have had already. He claims "all your father's want of principle you have inherited — no religion, no morality..." Nora feels betrayed by Torvald whose love she thought was genuine and not paternal.
Although she tells Torvald that she will not return, there is always the possibility that she will emerge stronger and therefore feel better equipped to look after her children again. Whether she and Torvald could ever reunite depends on whether he sees her as more than his "little squirrel."
It is possible to interpret the ending in a more negative light, focusing on the seeming selfishness of Nora who needs to "find" herself and Torvald who does not feel any gratitude for her sacrifices thus rendering him incapable of understanding. That is up to the reader.