My speakers are 32 and performing well. It depends on the components and materials. Foam surrounds tend to go in about 20 years, depending on humidity and temps...rubber surrounds can last much longer, but I haven’t reached the point yet where I can tell you what it is. Any pots can get oxidized at about any time, but most definitely will grunge up at some point. Good caps can last a really long time, but after 50 years lots of people replace caps in electronics...not so sure about speakers (they see a lot less heat). I replaced the ferro fluid in my tweeters at about the 30 year mark. All else is near mint on them.
Enjoy your new speakers!
Enjoy your new speakers!