Rick,
The answer to your question (IMO) depends on the chip.

For example, I doubt that calling in the $25 Hard Rock Cinco would have much effect on the value. It's high now, and would stay high.

On the other hand, If there's a $5 LE with a high issue number, and a dealer had a large quantity, I think he'd turn most of them in after a redemption notice was posted....

As long as a chip is current, or "live" it can't go below face value....after it's obsolete, it can. Every now and then, on the board, you'll see where a dealer will post a "last chance" on chips that he's going to cash in just before they become obsolete.

That's my opinion, anyway!