Yes, it is certainly significant that the questions remain unanswered and that the poem ends with a question and thus with no certainties for the future. The unanswered questions are functional to the main themes of the poem. The dreamer is left with no answers as to the future of his dream which represents the hopes for equal rights between white and black Americans. This adds to the general sense of frustration. But the lack of answers also has an effect on those white readers that in 1951, when the poem was published in the collection Montage of a Dream Deferred continued to deny African Americans equal rights. This lack of answers creates a sense of doom and threat for the larger society, especially because the italicized question that closes the poem warns against the rage and violence that the frustration of living in a racist society could generate.
In addition, the six questions and the two dashes create a broken rhythm that contributes to create a sense of instability and emotional confusion.
it is significant because here by starting the poem with a poem with a question the writer has put it straight into the reader's mind as what will become of the deferred dream. he wants to know the views of the readers too