I'm sure some of these coins will be redeemed.  If the private key isn't there, it will become public news pretty quick.  Why does everyone trust Casascius coins?  Since so many have redeemed, it is logical to assume that Mike Caldwell did defraud anyone.
   I bought an Adam Smith coin.  I can tell you that this would be difficult to counterfeit, so the chain of custody is far less critical for resale than other physical bitcoins.  Furthermore, making a custom made case such as they have would cost literally thousands of dollars for a mold...not to mention they have a very unique method of sealing the case that they haven't disclosed. Also, they have a proprietary cipher system for each case.  This means than you can take a photo of the case and coin, email it to the company... And they can determine if its legitimate vs counterfeit.  I seriously believe that if bitcoin reaches a value of $100,000, these coins would still be fairly safe from counterfeiting.