To me, Vudu is the likely company to make another step. great thing about Vudu if you have a PS3, you can download the HDX movie file and it takes streaming quality out of it.
I think everyone ran into stream only too soon. Vudu started out as a download service and then pushed it to the side. The ideal setup would be something like a WD box or a Roku with an external drive, and Vudu allowing downloads. The avg HDX file is around 7.5 gigs, so what would it add to throw a lossless track on there. Shoot for a 10gig HDX movile file with DTS-HD or TrueHD. It could be the case where the studios still want to limit downloads so you buy the disc too. Unless we get better internet options in the country, streaming only for people who care about blu-ray video and sound is a no go. There is nothing at my 6mbps DSL speed that would make me want to leave Blu-ray behind.