I don't see DRM as the issue here. If you purchase something and the terms of the purchase are that you can access it "as long as the company allows you to access it", this is different from a legal agreement that requires the company to provide access to it indefinitely. Something like Netflix has nothing to do with DRM because you are not purchasing content, you are buying access to it.
The idea that companies can just on a whim take content away that you purchased, no they can't, unless you agreed to this when you purchased it, or if you never actually purchased it in the first place. And why would companies go away from "selling" content and move completely to a subscription model. Last time I checked, they make a lot of money off sales. Why would they want to stop doing it?
A lot of people claim they want to own physical or digital copies of everything locally. That's fine. But I think more and more people are moving towards just wanting "access" to things, and not having to worry about managing files and discs themselves. And if a digital purchase is guaranteed to be permanent, it may be even more valuable to some than a local copy (which can be broken or lost).