Changes in speaker technologies are far more incremental than monumental, KEF Meta being a perfect case in point. Foam surrounds definitely have a 'use by' date, especially if exposed to sunlight (UV), and caps do age, although their lifespan is generally decades. But basic design and execution are far more timeless. Witness vintage Altec, JBL, and even the humble Large Advent.
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Do you believe a speaker's components like drivers and crossovers can become "outdated" for lack of a better word?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?