How long should high quality speakers last?

I would not even think about this issue for about twenty years. I would examine the woofers edges for deterioration of the tape between mount and cones. Nothing wrong with examining it early. I bought four 800 Series B&W speakers and ended up getting them all re-taped at around 25 years. Other than that, they should be good until you want better performing speakers. Typically for me that is every 10 - 15 years.

It really depends on the speakers.  Foam surrounds can rot after 20 years or so.

Mine have butyl surrounds and are 35 years old. 5 years ago I refreshed the ferro fluid in the tweeters. They’re as good as new...maybe better because the caps and woofers have thousands of hours on them.  Hoping to get another 30 years from them. 

It’s a good practice to rotate your woofers 180 degrees every decade or so to offset for any gravity pull.

I think on their site Zu says "100 years"     Enjoy

My speakers are forty one years old, they look and sound like new.

Mike

Speaker life depends upon the design, environment, and usage.  I am not familiar with your speakers.  From a design perspective, ware of the basket of driver is material dependent.  Foam wares sooner than rubber as an example.  The driver diaphragm is also material dependent.  Metal and composites are more durable than paper.  Environmental factors like heat and humidity affect materials of construction.  Aggressive home playing conditions of professional playing conditions shorten life span.  Crossover design with electrolytic caps may need cap replacement after 10-12 years.  You should inspect these items for ware.  If there are no signs of ware and your speakers sound good, don’t worry.  This still appears to be a current model. So that’s comforting from a repair perspective.  I have one of my first low end audiophile speakers, a 40 year old pair of DCM Time Windows still sounding as they did back then in a vaca home in VT.  Do they sound as good as modern designs … no.  But they have not deteriorated and sound as they did back then.