Climber Steve brings up an important point. Much of the conversation in the hobby has moved away from stamp shows and dealers with face to face discussion, to broadly based forums on the web like this one. The individual expertizer might seem an anachronism in that environment. Altho PF and APS have long used committees, I bet individual shops like Bill's were much more prevalent in the past than they may be now. Now that grading is the rage, committee's are all the more important.
Having said that, I still miss Bill at APS Summer Seminar. He taught classes designed to build knowledge in individual collectors, and he pushed eBay
hard on getting rid of the phony stuff you see there so often. He was an individual really working for the best of the hobby. That selfless attitude is less visible in the trends in the hobby that Climber Steve refers to.
I don't think I would throw away a cert simply because the fellow is gone. His expertise is still valid, until more quantitative tools become available. If the technology improves in an area, then resubmit.