Take Caesars Palace LV for example.
I believe Im right in saying there has never been a redemption order for a single chip. You can walk in and cash any chip they ever issued.
Most of those issues were 'retired' years ago. They are not in use and the cage wont sell them to you (unless you ask the right person 
)
The majority have probably been destroyed but I couldnt be sure.
At any time they could bring those chips back into play or issue more.
I would argue they are 'retired' but not 'obsolete'.
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