A roadmap is a visual representation of how the product will evolve in the future. In theory, it helps align teams and manage expectations. But it is important to use it with caution. 

It is essential to understand that a roadmap is a hypothesis that will be revised.

• The further into the future, the less detail.
• Communicate direction, don't give exact dates.
• Update it whenever you learn something new.

The roadmap adapts to reality, not the other way around.