What if the service goes belly up, or some legal squabble forces access to the content to be pulled?
So far it's been okay. For example when "Target Ticket" closed doors, there was plenty of warning and they partnered with VUDU to transfer all of my titles. There are some infamous examples like the "Amazon 1984 Incident", but those are quite rare. Almost certainly far more people have lost their physical media due to the dog eating it. You could also have a fire, flood, theft, warped/melted media because the car got too hot, toddler used it as a hockey buck, or whatever else.
Physical media doesn't just get destroyed, it also becomes obsolete. 8mm, tape cassettes, Beta, VHS, HD-DVD, 8-track, Laser Disc, CDs, DVD, vinyl records, DVIX. Heck, Warner Brothers HD-DVDs literally have bit-rot that made many of them unplayable after just a few years.
UHD is coming, so BD will be obsolete too. BD 3D titles are going to be obsolete first, with all major manufacturers having dropped that feature in their current lineup of TVs. If my current 3DTV dies, how will I watch my 3DBD collection?
Even if the format isn't obsolete, the content can go obsolete with extended cuts, director cuts, special editions, remasters, etc. If you love physical media I bet you've done this too, just as I have...virtually everyone buying physical media is familiar with the concept of double dipping, triple dipping, etc. In fact, I've bought Top Gun 5 times... VHS, Laserdisc, DVD, BD, and 3DBD. I am now considering double/triple/quad dipping on some UHD titles.
Now contrast that to iTunes, who upgraded everyone for free from 720 to 1080. And now they are doing it again from 1080 to 4K. I don't remember my VHS movies getting free upgrades.
And there is the sheer volume of the physical space they take. My dad has boxes and boxes and boxes of DVDs, VHS, Beta, Laserdisc, audio cassettes, CDs, and vinyl. These moving boxes go with him every time he changes apartments. They never even get opened--they just sit there in depressing stacks of obsolete media as a reminder of glory days gone by. I even found a box of reel-to-reel audio tapes for crying out loud. Then there are those vertical racks that hold movies; they just seem so...ghetto. I hide mine away behind doors.
Yeah I know physical media still looks and sounds better. But frankly, there are times when streaming is better as well. I had an unexpected 6 hour wait in the hospital while my mom had a procedure. Can I play my laser discs there? What could I do with a Redbox DVD rental? How about an UHD disc? Nothing. I can stream though. One of the best features of many current BDs is, somewhat ironically, that they often come with a streaming code.
Anyway, I say this as someone who
actually prefers and still buys physical media. I have cassettes and VHS and laserdisc and HD-DVD and Blu-ray and 3D Blu-ray and vinyl and now BD UHD.
I know the problems with physical media because I live it.
You could list all the problems with streaming and I'd agree with you--I'm just pointing out that neither of the methods are forever and both have many,many problems.