depends on designs, but I have a 1895 edison horn that still works ;) Caps change values with age,surrounds rot, paper surrounds last a long time but driver cones get brittle with age. I have had more than a few voice coils drive right through paper cones on vintage drivers.But over all a good design should last 25 years or longer with repairs. 10-15 without service.
Speaker Lifespan
Barring a blown driver, tweeter, etc. How long before sound starts to obviously degrade? I have Mirage Bi Polars that are 12 years old. Not looking forward to replacing them.