That's a gorgeous speaker, where do you live? Near NJ, USA? Can I invite myself for a listen? Yes, I would expect to keep them until I'm gone.
My drivers and crossovers were all made in 1958 (I was 10 then).
I have replaced the 15" woofer cones 3 times over 63 years (not separate foam surrounds back then). Once by a pro; twice by myself.
horn tweeters and horn midrange impregnated linen, nearly indestructible, UNLESS you over-blast this:
https://www.google.com/search?gs_ssp=eJzj4tFP1zcsNjAtKsqqLDBg9BLKzFNIVEhPTElJVACissyURAC2Sgq7&q=...
I burnt 2 tweeters, nothing since then.
Crossover is a tar filled can, newer open crossovers can be repaired, upgraded, that won’t be a limiting factor.
I also have L-Pads (speakers in that era were designed with flexibility in mind), I just replaced them, inexpensive and easy to find and do myself.
True Longevity: buy spare drivers at some point before you cannot get them anymore.
........................................
Substitute Drivers, i.e. a different tweeter, can be done and possibly be better: reliability, sound, or both. JSE Infinite Slope Model II’s used Dynaudio D21 Tweeters. I got my speakers used, great price ($700/pair) with burnt out tweeters, replaced them with D21’s. All set, except: Every party my teenage son had, they burnt one or both of the tweeters. It cost him $60. each tweeter way back then. After a while, I researched, found some Focals with near identical specs, matching sensitivity, better ferro-fluid cooling, got confirming advice from Madisound, used them, they are still tweeting.
My drivers and crossovers were all made in 1958 (I was 10 then).
I have replaced the 15" woofer cones 3 times over 63 years (not separate foam surrounds back then). Once by a pro; twice by myself.
horn tweeters and horn midrange impregnated linen, nearly indestructible, UNLESS you over-blast this:
https://www.google.com/search?gs_ssp=eJzj4tFP1zcsNjAtKsqqLDBg9BLKzFNIVEhPTElJVACissyURAC2Sgq7&q=...
I burnt 2 tweeters, nothing since then.
Crossover is a tar filled can, newer open crossovers can be repaired, upgraded, that won’t be a limiting factor.
I also have L-Pads (speakers in that era were designed with flexibility in mind), I just replaced them, inexpensive and easy to find and do myself.
True Longevity: buy spare drivers at some point before you cannot get them anymore.
........................................
Substitute Drivers, i.e. a different tweeter, can be done and possibly be better: reliability, sound, or both. JSE Infinite Slope Model II’s used Dynaudio D21 Tweeters. I got my speakers used, great price ($700/pair) with burnt out tweeters, replaced them with D21’s. All set, except: Every party my teenage son had, they burnt one or both of the tweeters. It cost him $60. each tweeter way back then. After a while, I researched, found some Focals with near identical specs, matching sensitivity, better ferro-fluid cooling, got confirming advice from Madisound, used them, they are still tweeting.