...is that the sounds change(d) so fast whereas a guitar or a piano still sound like a guitar or piano (well, there's a lot of effects and stuff you can put on it but that's technology too). However4, I think many supertrendy sounds can date pretty well. For example, Prince's "1999" album was very trendy soundwise and it sounds good today I think (it sounded pretty lame in the early 90's though IMO but that's because the 80's just went overboard with it after a while so you needed a break from that type of technology IMO in order to appreciate it again)-I don't think there's any rule for how you can tell if it will come back or not. Maybe the Shekspere sound you hate will come back too you know?

A lot of people say that good songwriting survives but I don't really buy that because songwriting actually change a lot too. I remember that the damaja used to say that songwriter Burt Bacharach's many hits in the 60's (think Dionne Warwick) could become hits today again in more modern arrangements but I don't think so; many old melodies-regardless of how good and catchy they are-just sound old fashioned in their rhythm, intervals etc.. Hits in major scales for examples are much rarer today than in the 80's...