It isn't just the product itself: he's saying traffic to the site has dropped substantially, so any product will be harder to sell now for them.
Some people who would buy the higher quality templates don't know that they exist now.
Some people who would buy the higher quality templates don't know that they exist now.
But the broader, more important point: an open source project previously could be funded by using attention to sell other services or add-ons. But that model might be gone if users no longer visit or know the creators.