"As good as Eric Darling and John Stewart and Frank Hamilton were, no one could replace Seeger, and it just wasn't The Weavers anymore."

You will get some arguments there. The Weavers made some wonderful recordings with Darling and Hamilton. Darling's musical expertise especially added a new dimension to their music. Don't overlook the contribution they made!

I assume you meant John Stewart in the Kingston Trio, not the Weavers. Even though they didn't have the huge hit singles, the Stewart years are generally recognized for the artistic growth that the Trio had. Some would even say their best years were with Stewart!

"contemplate Peter Paul and Mary retiring individually, but finding replacements. Eventually we have a trio composed of Fred, Lloyd, and Virginia. Is that still "Peter Paul and Mary?"

That is too hypothetical to consider. Considering that the trio has been together for 40 plus years, it isn't the same as a group that has evolved through changes.

PPM was a manufactured image - but one that works dramatically well. Plus, Noel "adopted" the name of Paul!! I wonder what would have happened with the original trio that Albert Grossman wanted - Bob Gibson, Hamilton Camp and reportedly Marilyn Child.