Time moves back and forth in the novel, from the the 1980s to the near future. This glimpse into Sasha's future emphasizes how we experience time - slow in the moment, but incredibly fast when we look back on our memories. It also emphasizes how we experience change.
In this moment in Naples, Sasha can't imagine a better life for herself. Yet, 20 years later, she somehow finds herself in a comfortable, happy life looking back on her former years. We often don't notice change happening until it's already past.