How long do high quality speakers "last"

Quality speakers are made to quality standards and can last for decades.

I have a pristine pair of ADS L-520's that I bought new in 1980.  They are currently used in a secondary system.  They have been well taken care of, not exposed to temperatures extremes, driven with only quality electronics and their woofers use butyl rubber surrounds that will last forever.  So I see no reason that I can't get another 36 years out of them.

Wondering if the OP will see this and chime in on the condition of his Response 2's now that they are roughly 22 years old.  

I have a pair of Kef C55 that were purchase about 1990 that still sound fantastic. They have taken quite a beating, too.

I expect my Silverline Preludes to really last as they have magnesium/aluminum drivers and rubber surrounds. The crossover caps may die before the drivers, but I’ll likely get bored and replace the speakers with something else due to boredom or curiosity well before any of that. Note that I use my trusty old Boston Acoustics A60IIs in my TV system and have replaced the woofers once (foam degradation). years ago…they still kick a--, so to speak (from 1988 or something?). I assume the ferrofluid will dry up eventually in the tweeters but so far they work fine.

The question responders should ask of the OP is, physically or technologically.

Larry