I like the password change idea, with the caveat of instead of deleting the account after "X" amount of inactivity, we archive it. Sometimes there are Amabassadors whom love Fedora but get wrapped up in the dealings of daily life that they don't have time or gumption to keep track of their Ambassador status. However, that doesn't mean they wont ever return, and we shouldn't just get rid of their wiki, account, and other materials because they have gone inactive.
I am in the same boat, almost. I love being an Ambassador and when I signed up, I had free time and could devote alot to Fedora. Since then, I have decided to go back to college to earn my MBA (tough to do when you got your undergrad 8-10 years ago) and still work a full time career. This leaves me with very little time to travel and devote to Fedora. However, once I graduate I plan on becoming more active in Fedora again, and if my account had been deleted in my absence, I would be less motivated to sign back up.