Depends on how far back you go. Example: speaker surrounds before the early-mid nineties were made from perishable materials. Not anymore. However, electronics always age but in my experience fail only occasionally. A ten year old speaker should be fine unless it was really abused - which is rare
Buying used vs new speakers from a technology perspective
Do you believe a speaker's components like drivers and crossovers can become "outdated" for lack of a better word? For instance say someone is selling a pair of speakers that cost $10k in 2008 for $5k now. Comparing that speaker to a modern day $5k new speaker only looking at driver design/drivers, cabinet construction, crossover components/layout and other materials what kind of technology gap are we looking at?
Have there been technologies or designs that have come out in the past few years that you couldn't live without after hearing?