These are all excellent reasons and pretty much cover why I collect physical video media.
I am sure the studios will try to totally push us into downloading and streaming eventually. It's going that way already. That's why TWILIGHT TIME is called TWILIGHT TIME. It's one of the last gasp attempts to enable us to fill in gaps in our collections with quality transfers.
The studios want to reclaim complete physical control over their libraries, and they want to reclaim total financial control over their libraries without expending much in the way of distribution costs. Putting the films in the cloud or on a hard-drive in the CEO's closet costs them very little.
So......I'm collecting all the physical media I can which interests me, either as purchased software, or as recorded off TV material.
Bogart said to Bergman, "We'll always have Paris!"......and I say, "We'll always have physical media of our favorites to watch---if we collect it now!"
You'd still have to back up your disc bound stuff because eventually, the possibility exists the disc drive hardware itself may become obsolete. My local computer hardware store no longer sells IDE drives. I bought a couple of them years ago as safeguards, but, it's possible that if they are ever used, they may outlive the machine which hosts them.
Things will inevitably become more complicated. It all depends on how convenient backwards-compatibility is coupled to forward thinking.