"So, 1H02 the Thoroughbred, 2H02 the Barton...Why not just wait for the Barton then?"
The Thoroughbred is more of a test run for AMD. It is their first release of .13 micron parts and they need a guinea pig. Since the Thoroughbred has no major changes from the current Athlon XP, it is an easy test and few people will care if the product has some initial production delays since they can just get the current Athlon XP. Once AMD perfects the .13 micron process, they can confidently release the Barton with major changes.
"I doubt they'll even release the Barton when Clawhammer is just around the corner."
The Clawhammer is for high end desktops and workstations. It may very likely cost almost $500 on the street to purchase when it is first released. This is not going to be a huge seller initially - thus AMD needs the Barton for the majority of users who don't need 64 bit and don't want to pay the price premium. The price will decrease over time, people will eventually need a 64 bit processor, and the Clawhammer will slowly become more mainstream. But Barton is needed until that occurs.
"I have a feeling that the Barton will turn out to be the Duron of its time while the Hammer will be the Athlon."
The roadmap that NFS4 posted clearly shows that AMD will have three desktop processor lines: Value processor will be the Duron probably until the end of 2003, Barton will be the Athlon into at least 2004, and Clawhammer will be a third high-priced high-performance line. Only near the end of 2003 or longer (as market requires) will the Duron die off making Barton the value processor.