The answer to your question is yes, the CS brains trust has diminished over time. A pity as the forum needs more experts with true perspective gained from having tried a wide range of equipment and coffee. Unfortunately, some had commercial interests that led them to pushing their own barrows a little too hard. Others strongly believed that their way was the only way.
Will they return? I hope so but that is their decision. In the meantime, CS needs to keep on moving. In my early days, I put forward the idea of having FAQs to address the common questions such as what machine should I buy or why are my shots no good. Now, I think it is important that we continue to have and answer these questions to help ensure the survival of CS.