The interviewer is hoping to hear that you will stay with their company long-term.

If you are currently going to school, share that you hope to stay with the company at least until graduation. Mention what you are going to school for and when you plan to graduate. If the company offers careers in your field of study, such as management, be sure to mention that you would be interested in considering a management opportunity upon graduation.

If you are not a student, that is great! Simply tell the interviewer that you see yourself still working for the company. Next, mention if you hope to receive a promotion at some point. State the title of the position you would like to be in, and mention that you understand it will take time to achieve this level. If it happens within 5 years, that's great! If not, you will continue to learn as much as possible now until the promotional opportunity becomes available.