How long do high quality speakers "last"

holy moly

21 year old post!!

still relevant tho.

ACOUSTATS LIVES FOREVER!!!!!! and still playing since 1982. Had a friend over to hear them and he gave his maggie's away!!! now what does that say.

I've had my Thors 18 yrs,, no issues, except the foam diaphrams in the Millennium's diintergrtaed,, so replaced,, still my tech guy tested them, and suggested replacing at $300/each,, the speakers were not  is use but 8 of the 18,,and not loud, nor much R&R, mostly classical,, so lightly used. 
This gives you a idea of when to change mid wteeters,, midwoofers are perferfect,,except my cat long ago scratched 2 mids so recently i myself replaced the 2 surrounds, very easy to do.
just added  new high tech xovers,, so a   good speaker over say 10 yrs old, recommend replacing mid tweeters and also upgrading xovers.
Hope that helps. 

A lot of good advice given above; the rare thread that, so far, does not include crazy accusations about other comments/commentators. 

I have not heard any bad comments about ProAc speakers going bad, and I've seen a few older models that are in good working order, so I would guess that they are not particularly prone to early senility.

Speakers age at vastly different rates so there is no handy guide as to how long to expect any given speaker to last--it depends on design, materials, and environment.  I have a local dealer that makes custom speakers out of mostly vintage parts, some of which are extremely old.  Most of the woofers are from the 1940's through 1980's, and compression drivers can be much older than that.  In my own system, I run a compression mid-range driver that is just a bit over 80 years old.