The ones that open up and leave are the ones that are looking at the short term gain. If you are serious about it, you need to be in it for the long haul. No, I do not think the niche's is saturated. I think its full of a lot of crap, but of the quality sites, I think there are always room for more. Do keep in mind that many paid directories start out free and then close the doors to free links in order to again, build value to the directory be decreasing quantity and increasing quality.