All too often people mistakenly think they own their games, even the ones for which they have physical media. With traditional media you own the physical discs but they're really just a practical way of installing the media to your computer, you don't actually "own" the game, you own a LIMITED licence to play the game.
So the issue is really just a case of having a safety net for if anything happens, as long as you have the physical discs then you're happy because at any point in the future regardless of your actions or the state of the business, you can always access "your" game.
Steam is just a better way of delivering that content to PCs, physical media is next to dead now, but it does raise the question of what is our backup. Thing is though is that we already have that, pirate media is floating about the internet and is just as easy to obtain as downloading games on steam, in fact steam is popular primarily because valve knew they had to alter the convenience of distributing games to be at least on par with pirate copies.
With the ubiquitous nature of pirate material online I don't think anyone should really be concerned with digital distribution, paying for media these days through steam is more or less just a formality, I know many friends who are still paying for releases through steam, but also downloading the pirate version of the same game because it's better for some reason, either it was released earlier or has some other benefit like not wasting an activation, having bloatware like GFWL hacked out, and stuff like that.
In the same way that I know people who pay for TV subscriptions but then just download the episodes from the internet, if there's still some benefit to downloading it (no adverts, being able to seek through content, pause at will etc) then people are just going to do that instead and actually paying for that content through a distribution partner is merely a formality. Distribution of legit media is tending slowly towards the same quality as pirated material which is good because quite frankly pirated material is unquestionably better in most circumstances, but I think as that happens the lines people draw between consuming their media and actually paying for it will become more and more blurry.
I could imagine a future where we pay for the rights to play a game or watch a movie and not actually recieve anything for that payment, that we're at our own discretion to simply find that media online however we think suits us best, that's the ultimate distribution model right, it's basically what exists already except there's no way to pay for it, which is pretty dumb to be honest.