It's going to be very dependent on several things. How much use the amp has had, either being played through, or thrown in and out of Transit vans. Where it's been stored: damp basements or attics are its worst enemies.
Components will degrade with age, and speakers will suffer if the atmosphere is damp - as will any other electronic parts. The valves can easily be changed - and should be - but valve seats deteriorate, become brittle, and cause microphony. I remember changing them on 15 yr old amps from the '50s/'60s.
Soldered joints are infamous for 'drying out', but with a bit of fettling with a soldering iron will be good for many more years. PCBs crack, especially when an amp is dropped, and that, while not insurmountable, could be the cause of death to an old amp. Capacitors start to leak, so don't hold charge any more. Point to point is far better.
So, the answer is more no than yes, but most components can be replaced, with very similar sounds being available, or maybe even better ones! Judging by the amount of old Fenders around, others seem to agree!