I agree with Jay, that the term "obsolete" should be defined to the needs of the hobby. "No longer in use" almost gets the term correct, in my humble point of view. "No longer in use" can only apply to chips that were at some time in use. Many of the limited edition chips were never in use, sold out to collectors before they ever had the chance to be put on the tables or never even intended to be used on the tables. Also, the latest Caesar's $1 chip was no longer in use, but readily available at the cage for the asking, until recently. I wouldn't consider a chip to be obsolete if you could still get it at the cage. Also some smaller casinos in Nevada have closed their table games altogether and their chips are no longer in use. But some will allow you to buy the no longer in use chips at the cage.

I like to define obsolete as "no longer available from the casino". This would cover LE's and withdrawn chips still available at the cage. It would also cover Atlantic City where chips are always redeemable.

As a collector you are interested in collecting a chip. If the chip is not available at the casino, then it is obsolete. Another way of saying this is a chip is obsolete if the only way you can get the chip is through the secondary market (usually other collectors or dealers). The primary market being the casino itself.

Cheers.