This is Sad News indeed. Cassidy was editor of the wonderful "Dictionary of American Regional English" which had only reached volume 3 (I-O) [three huge volumes of the size of the OED volumes] -- here's hoping that somone is in place to continue his project!

and here's some words from volume 3, as provided by amazon.com: "If you jug-handle that kyoodle and make him meech, you ouchy numpy, we're bound for a real lip battle."