For example: the rock hall of fame as mentioned above not only looks for an age barrier (25 years) but “innovation and influence”. the film registry looks for films of “significance” in many faces (i’m disregarding the sports hall of fame issue here because i feel the creative ones suit something like anime more.)

Things like Rurouni Kenshin have become classic because of the impact they had on anime fandom (^_^x) as well as the anime industry. Recently reading through the manga again after recent re-reads of Bleach and Naruto have honestly made me wonder if the authors of both read Kenshin; it wouldn’t be hard to argue for that. Anime like Fullmetal Alchemist will probably become classic as well, because its spread is affecting both the industry and the culture (enough that you’d remove it because you think it’ll throw off the polls). However, FLCL, which lacks FMA’s monstrous market appeal (in my opinion) will also become a classic in time. The innovation gainax packed into those six episodes is hard to ignore.

Hmm. there’s my rather long two cents, then :)