My early 90s NHT 2.5s and 1.5s have been great over all these years but I somehow had a surround 'rot' on a 1.3 speaker, not sure why; the other 1.3 was/is fine still. My 1996 ML SL3 electrostatics with 10" woofers still sound great in my home theater.
I've got early B&W DM301s? 30+ years sounding fine as well. My brother's mid 90s Thiel 2.3s sounded superb two years ago when I last heard them.
I do think well made speakers, taken care of, will last quite a long time. More recent ones have the benefit of better engineered materials (if appropriate for the design).