The only thing I’d be worried about is the foam surrouds on the drivers....they will rot out after 20 years. Other than that, speakers have not changed all that much really. Old Tannoy, Altec Lansing, and Electro Voice Interface were some of the best speakers ever made and are still desirable even today.
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Do you believe a speaker's components like drivers and crossovers can become "outdated" for lack of a better word?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?