Unfortunately, I don't see glamour items decreasing in value for a long time. I think it's really sad that the most expensive items in this game do almost nothing for you (glamour/furniture). But, until Yoshi let's us crafters make something seriously viable end-game, I don't think this will ever change.

I hate to say it, but I miss the materia system from 1.0 where you could risk a ton of materia/gil to get a quadruple meld, but once you did you had something comparable or at least on par with end-game gear (and would in turn, be expensive and net a nice profit!!).