@immatthewj I'm sure you are right, I was answering the more generic question the OP posed in the title rather than the parenthetical one.
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.")