Not exactly, it is the only disc type to carry both 1080p Full HD video at 60 frames per second with stereo/Dolby5.1/Dolby7.1 audio. Digital download however can be just as good if not better, but most digital downloads don't include deleted scenes and other features you can get on Blu-Ray. Wait till iTunes comes out with special features for everything, then stop buying Blu-Ray.
I think so. Though I did notice that there is improvement with sound & quality when I watched some films with a friend who collects blu-ray discs, it's definitely not worth the extra money.
I think so. Not many people want to trade their large dvd collections just for blue ray. Ecspecially now with HD tvs. I don't think they'll ever be a primary source for home entertainment.