Gemini, I know how you feel. I may be moving to another city that does not have a gym affiliated with my current gym. There isn't much as far as variety either so branching out to a new art may not even be a possibility. However i cannot imagine not training in TKD so I will probably pick the gym most suited to me and when I get there I will work my butt off, for myself and out of respect for my instructor. Ya never know, maybe the new place will let me lead warmups, show some drills, etc.
I know when we have transfers, our instructor is always looking for what she can learn from that student that may help other classes. Hopefully I won't have to worry about this at all, but good luck to you Gemini!