Forever

Yeah..keeping in mind the idea that "Disney characters don't age", I could see him having very minor if any differences. I sometimes wonder if he was their master as well....But if he was, and Xehanort STILL turned out the way he did- Then....well, bad parenting Yen.

^I dunno about the 'Disney characters don't age' but I'd also consider Yen Sid a special exception, as if he had a sorcerer's stone and was semi-immortal or something. (Unpopular opinion: My headcanon is that he's actually Eraqus and Xehanort's master. I know there's virtually no evidence for that, and age is definitely an issue factor, haha...)

Nah, you're not alone. Its a rather popular thought. If not him, possibly someone from chi. I personally would love to see a young, energetic Yen!!

Nice avi, btw