I'm at almost 550 blu's so you can guess how I feel about physical media. I am still a hardcore home theater head running a Dolby Atmos 7.1.4 setup with an Onkyo 11.2 ch network avr, I want the best sound I can get. So far that is on physical media, I'll take it.
Although triple layer blu's (100GB) can support 8K you would have to upgrade HDMI cables and hardware. Short of computer bd drives, I don't think our current BD players can read triple layer disk, also every movie would have to have a 2nd disc for the extras. Then factor in that peeps would have to start their collection all over again and how many studios would support 8K disc production. We still don't have some movies on regular BD yet, let alone 4K.
Streaming is still heavily compressed due to bandwidth limits and lack of fiber Gig up/Gig down network infrastructure across the USA.