i dont think that directories will be devalued . they are one of the best ways to built one way backlinks. i think they will stay forever
By the way, IMHO, google , yahoo, msn, ask,,,, Are also directories, with a turbo charged search function, Ergo, whereas you don't use directories, a lot of new sites are going to get seen for the first time by people who find erm in directories often via SE serps Infact a satisfied visitor to directories might be inclined to return, For example , where they are trying out diferent suppliers for a service, my directories are very new, but already the stats tell an interesting tale
Google will not devalue all directories, ever. It is free labor for them -- HUMAN-editing is not Google's strong point. They see good, quality directories as their best free filter. If a site can get into a good, quality directory, it is probably worth indexing. Google MAY decide to devalue many directories, or perhaps take on a "Google Certified Directory" program where people can apply to have their directory included. If they had it their way, they would just use DMOZ alone, but the backlog is so huge already and if they made DMOZ the only source, it would be years before they could get to reviewing a submission. The key to directories is finding the real ones. I have a list of over 2500 human-edited directories compiled over the last 5 months (many from here). Of those 2500, I would say about 700 are good, 150 are indexed regularly, and under 100 are indexed deep enough to pass link juice.
As has been (well) said, the key lies in the degree of authority a directory happens to have and the status that, by implication, it can transfer to your own site. Whether you need to pay for inclusion or not isn't really relevant. What matters is the benefit you can gain by being listed "in all the right places." And one way to determine whether a directory has the authority you want is to browse through the relevant category to see how many of your competitors are already there (even if you don't think they deserve to be!). Duncan