How long does it take a decent quality speaker to "wear out"?

Good.  Just make sure you keep them away from running water 😃.  Actually, some manufacturers cite maintaining medium ranges of humidity as a way to ensure long speaker life.  Sounds reasonable to me.

50 year old ESL57’s

45 year old Cornwalls’s

50 year old Dynaco A25’s

All still working just fine :)

The ears usually wear out before the speakers do. Given some sonic degradation over time, it is likely so gradual to even be noticed, if at all, or subject to the “used to it” effect.  Playing or swapping out will produce sonic differences. Is the result an actual improvement? Only your hairdresser knows for sure. Exhibit A, most of this forum is dedicated to sonic perceptions 🙃

Totem Acoustic Speakers are made to last a lifetime. In addition they are designed to sound identical in any part of the world they are domiciled. They are absent of any wool or Acoustic filling that breaks down over time. 

@immatthewj 

Good question!

Other than the driver surrounds crumbling, I have never had a speaker “Wear out” I have upgraded crossovers because it was an upgrade, not because of any other reasons.