How long do speakers last?

I have 15 year old speakers and I cannot remove the sock but they work fine. Do I have to worry about woofers deteriorating or are there electronics (crossover?) inside which won't last forever? I don't use these much.
Once I had clipping problems (5 seconds) but it sounds OK. Did that damage the speaker?

Can any good audio repair shop refurbish these speakers?
Or should I bring to speaker rebuilder? (I live in Los Angeles)
You could contact DCM directly and get heir advice. Their phone is 877-326-5683, or thru their website:

I'm sure they still work on older speakers, You could perhaps just send them the drivers for rehab. I'll bet they can even sell you a new grill/sock.
It depends on the material and the enviroment.
Here is a pdf file on Rubber Products: Recommended Shelf Life
See Table I on page 5 for type of rubber, common or trade name and the shelf life.
Billy doesn't sound as good as he used to. Mayebe he was left in direct sunlight.
Rich, I thought the table you referred to was very interesting. Mainly, I was surprised to see such relatively short lifespans for materials that I thought lasted much longer (like silicone rubber and neoprene.)

Might be a good reason to get new cables and speakers every 10 years??

I drive a 33 year old MB that my dad bought new in '72. I now have visions of walking out one morning and discovering all the electrical insulation has turned to dust over night -- yikes!!

Luckily I don't have any rubber parts (so far!) but now I think I understand why some women are concerned over them ;~))