I had a full response written up before i closed the tab so I will paraphrase this one.

Every jurisdiction has different rules. In Nevada they are governed by the gaming commission. See document at http://gaming.nv.gov/modules/showdocument.aspx?documentid=2925 but there is no reason they have to. There are accounting/financial reasons why they would want to though (always the beancounters involved).

12.070 Redemption and disposal of discontinued chips and tokens.

A couple of sample notifications:

Siena: http://classifieds.rgj.com/item.php?id=2000058783&place=Legal&posit=Legals
Silver Star (non NV): https://news.google.com/newspapers?nid=1817&dat=19981021&id=4iEfAAAAIBAJ&sjid=UqYEAAAAIBAJ&pg=3553,4726919&hl=en
Riviera: http://webcache.googleusercontent.com/search?q=cache:3_7HJGD_f7YJ:classifieds.rgj.com/item.php%3Fid%3D2000051833%26place%3DLegal%26posit%3DLegals+&cd=3&hl=en&ct=clnk&gl=ca

It would be great if this is tracked somewhere. I updated the information on Mesquite as I was up there this last weekend and they had posted notices on the redemption period from their previous rack.