In reality, there will never be a final product. You will almost certainly have to change your product and innovate with time. This is where the Agile methodology can help, as it makes it a little easier to change your mind, or pivot. In fact, your originally defined product vision can even change. If you're in the early stages of testing a hypothesis for a startup, your vision may drastically change in six months. If you're re-building an existing mobile app for a client, the vision may not change at all.