That means not owning your games, and nobody wants that.

135+ million Steam users disagree with you, but that's not really the point.

Steam is far from perfect solution, but (let's call them) safeguards that open platforms offer are one way to be more at ease with technically not owning your games versus closed gardens that consoles are.

To get back to the point, being able to run (selected) Steam games on everything from $200 handheld/phone to $5000 PC is what Steam is headed toward (and is already there to a degree) - and I can't see any other digital platform trying to do that.

But the point of paying for a game is to own it.

And you de facto own them on Steam, and you will not loose your games...one way or the other, which is not necessary the case with consoles. 

Even with GOG it's actually license, not real ownership, although there is zero DRM and you can pretty much do with your downloaded copy whatever you like (though most of it is still not legal).

And no, I don't think unique ID digital copies that you can resell on platform that hosts it is something we can expect, even if they make it so that platform and publisher get the cut of that sale as well.

Well it's what should happen anyway. Better than losing access to your games just for being inactive.