How long should speakers last?


I've had a set of NHT 2.5i speakers for 18 years. They still play great. How long should speakers last? Is there a rule of thumb?

I am about to purchase a similar age set of mirage m3si. Assuming they were well taken care of, how long would you expect they last?

Thanks!
sm_76
Caps and foam surround can go but are serviceable. Therefore, speaker can last forever.
For what it's worth, my 1997 Mirage M190is pair still does daily service in my office system. Butyl surrounds last quite a while.
I have 1996 Aerial 10T, but I replaced blown woofers on both due to the cranking habit:-)