Perhaps you could think ahead to the type of things you would want to do after retirement and there may be some synergies there between what you do now and what you want to do after you retire. That way you could still mention goals and still come across as an ambitious person, but that strategy allows you to be less specific about the fact that these goals don't include that specific workplace.
For example, if you want to retire and travel, say you have an interest in learning new languages and cultures. Maybe they'll put you in a cultural diversity training class, which helps you both at work and in retirement.
As a side note, be sure none of the offerings tie you to working there beyond your retirement timeline. You still have 6 years, so it's probably not as much of a concern now, but as you get closer to retirement you may want to be more careful with that. I think I'm on a 4-5 year timeline and my employer offered college coursework with a 2 year contract (you can quit at any time but you'd have to pay back the tuition). Since I'm on a 4-5 year timeline, a 2 year contract was fine by me, but I'll think twice about that as I get closer to the end of working.
Also, don't feel bad for "only" staying 6 more years... that's a long timeline by today's standards. Having an employee you can count on for 6 years is worth the investment IMO.