An update on my earlier post....
Summary of the previous: I had encountered this thread only about a week or so after booking all flights with United and sending in deposits on all lodging and diving. We called United and found that our flight from Yap to Palau had indeed been canceled. They apologized for the fact that we were never notified. (In fact, the flight was probably already non-existent when we booked it.) When we called, they told us to hold off canceling things for a while, because the route might be reinstated.
Update: We are traveling with another couple, and when they learned about this from us, they also called. They, however, were given a different prognosis--there is no possibility that the route will be reinstated. Go ahead and cancel all your plans.
We had done a lot of planning for this--many, many hours, not using any agents. We had considered a number of alternatives, but rejected each for various reasons. We are back to square one now. We are scrapping everything and looking for a nice two week trip somewhere in the south Pacific, possibly the Solomon Islands. We are all entering a busy time for all of us, so we will probably just tell a dive travel agent roughly what we want and take what we can get.