In that case big ISPs and the fall of net neutrality will save Blu-ray. I wouldn't rule out physical media so soon. If the all you can download Internet model goes away (and let's hope it doesn't) things will progress very differently.
Even discounting the 'net, what about encrypted broadcasts a la DirectTV? That might be a better way to do HD content delivery in the near future anyway.
I don't think media like this is going to last more than one more generation. If that.