I have 30 year old Legacy Focus and Signature III speakers in my listening rooms and two pairs of 1970s/1980s speakers (one being ADS L620) for my TVs and had to replace only one, non-butyl surround on my Sig IIIs (bottom woofer). They play better than new. Truly, speakers can last one’s lifetime. In storage-Dynacos 25, 35 and 50 speakers-perfect condition.
How long does it take a decent quality speaker to "wear out"?
After all, they do have moving parts and capacitors. . . .
(I suppose that "decent quality" s a relative term. FTR, I am running a pair of the older B&W 805s, and for all I know, they may not actually meet the criteria of "decent quality.")