Maybe it is just a question of location, or whatever, but I get at least three or four requests a month for references outside the area I cover.  I am happy to pay the subscription so I can check out what the listing look like and give my clients the best guess as to who to call.  I always ask them to let me know who they choose, and how they felt about the product they received.
I do think you are correct in thinking that enhanced listings will be more valuable than they are now.  For myself, though, I will continue to look at both types of listings.  I would not want to limit my clients choices to only those that wish to spend money on the enhanced listing.