TNG on BD even with all the problems they have had is still worth every penny. The releases certainly have not been a fly by night cash grab that the feature films have been. I'm hoping the work done on 'Birthright' in season 6 will drum up some interest for DS9 on BD.
I expect that will be the case. I think it will be similar to when we saw Trials and Tribble-ations for the first time on DVD and everyone was marveling on how amazing the Enterprise looked when it first appeared on the viewscreen. I've got a feeling DS9 (The space station that is) is going to look absolutely spectacular in HD, and it will whet the appetite to get the series on blu-ray.