In I Know Why the Caged Bird Sings, what insight into the future does Maya Angelou seem to gain after recounting the past?

After recounting the past, Maya Angelou realizes she has the ability to thrive despite the insidious influence of racism and the dysfunction of her childhood.
Maya comes to see her past experiences strengthened her resolve to live victoriously and confidently. In the introduction to the book, we are told Maya wrote her story because of her grief at Martin Luther King, Jr.'s death. In recounting her past, Maya is able to make peace with the imperfections in her life and accept that her place in the future need not be defined by the mistakes or the trials of the past. Essentially, she can be as successful as she chooses to be; in this, she remembers her mother's advice:

On my way out of the house one morning she said, “Life is going to give you what you put in it. Put your whole heart in everything you do, and pray, then you can wait.” Another time, she reminded me that “God helps those who help themselves.”

In recounting her past, she realizes those who love her will always support and encourage her in her time of need, and she draws strength from this knowledge. In the book, she recalls how she was raped by Mr. Freeman, her mother's live-in boyfriend.
She was only eight at the time, and the experience was painful, humiliating, and dehumanizing. She recalls that Bailey managed to wrest from her the identity of her rapist. Maya relates how her brother wept at the side of her hospital bed when he discovered who raped his sister. She maintains it was fully fifteen years before Bailey cried like that again. During her recovery, her uncles guarded her, and Bailey read to her for hours.
Maya eventually manages to overcome her trauma, and she goes on to become the first black streetcar conductor in San Francisco at the age of fifteen. The book ends with Maya learning she has what it takes to be a good mother.

Mother whispered, “See, you don’t have to think about doing the right thing. If you’re for the right thing, then you do it without thinking."

So, in recounting her past, Maya realizes strength is gained from adversity, and each acquired victory is a testament to the power of the human spirit. This knowledge allows her to look forward to the future with confidence and courage.