It is difficult to argue that this play is either a classical or a modern tragedy, as the ending of the play does seem to offer a measure of hope and also to represent a new beginning for Nora and the empowerment of women. This distinguishes the play from other tragedies, which normally feature the death of at least one if not more characters.
Arguably, it could be said that this play does have elements of both classical and modern tragedies. For example, some critics argue that Nora does have a hamartia, or a tragic flaw, in her propensity to lie. It is this deception and the way that she keeps truth from Torvald that is eventually unearthed and forces her to undergo an epiphany about her character and the way that she has been kept like a doll in a doll's house, without ever having to grow up and face maturity. In the same way, the play uses a setting and raises social issues that are particularly fitting for a modern tragedy, as Ibsen discusses gender roles and the institution of marriage.
However, the way in which Nora faces the truth that she realises and then acts on it, determined to live her own life and to do so free from the "stranger" she realises she has been married to, offers a considerably different ending from the normal ending of death associated with both modern and classical tragedies. Note what Nora says in the closing lines of Act III:
You must not feel in any way bound, any more than I shall. There must be full freedom on both sides. Look, here's your ring back. Give me mine.
The way that Nora embraces "full freedom" and walks out the house, slamming the door behind her, offers hope for women and of freedom and escape from the oppressive nature of being kept like a doll in a doll's house. This ending ensures that, although there are tragic elements to this play, it is indeed no tragedy, in either the classical or the modern sense.