How long do high quality speakers "last"

The RMa's don't use foam surrounds, so I would investigate using a high quality rubber preservative on the butyl every 2 or 3 yrs or so to keep the butyl from drying out (micro cracking) and will help keep them pliable...there won't be any change in sound or performance when you apply it or anything, but it's a worthwhile investment for what little it costs. Be sure to keep your speakers out of the sunlight, even through glass. Not only will it begin to mar the finish over a decade or two, but if you leave your grills off it will slowly degrade driver materials and surrounds as well, IME.

If you're worried or just want to know what your fall-back options might be, give Lou Hinkley a shout and see what he offers in the way of refurbishment (or what drivers or materials he'd likely be able to send you, if you can do that sort of thing yourself)...it might be well cheaper than replacement if push came to shove.

Ivan, Thanks, that's helpful. Unfortunately my speakers are the wrong side of the pond, in the UK. Transport there and back is pretty costly. Lou has been anxious to get my speakers the V2 upgrade, or switch to Athenas. I would need to sell mine first and have had no interest in trying to sell in Europe. The name is'nt known here, much to Europe's loss.

How long do B&W 805 Nautilus last?If I take good care of and not playing them loud?

mshan  How long do high quality speakers "last"

First off you have, one of the nicest sounding semi bookshelf's in the Response 2. And they still demand good money even today.
 
Foam roll surrounds are the best, but do rot and should only be replaced with exact same ones. As the "compliance" of the roll surround is part of the Thiel & Small parameters that has dictated your box and port size to that base driver.

I would also every 5 or so years, rotate the bass driver 180 degrees, as the cone/roll surround will sag unevenly and could eventually cause what's called "polling", this is where the voice coil is no longer in exact center of the magnet gap and starts to touch/scrape it.

Cheers George