My colleague in Charlottesville, Jim Duncan, has a post on houses that don't sell, just because their buyer isn't currently in the market.
It's one reason why so many people want to be "the third real estate agent." (Old real estate joke. You're going to have to ask me privately!)
I think Jim's got it right, as usual. But it's a hard conversation to have with a seller. It's human nature to reject what you don't want to hear and I suspect most sellers will send you packing the first time they hear this. (And, maybe a few more times!)