SimonG: Well you
can rent it sell it and borrow it. But that is a breach of the EULA and illegal. Games, even the boxed one, were sold as a license meant for personal use. E.g. "Blockbuster" or other rental services have a different, significantly more expansive license to actually be allowed to rent out a game. "Borrowing" is somewhat of a grey area, usually it's never prosecuted, but that doesn't mean it is something you are allowed to do.
Generally a DRM has nothing to do with the rights you have with a game, it is simply a matter of enforcement. Therefore the only things that changed were ways of the
right holder enforcing their rights, nothing more
And you never "own" games. Electronic Arts and Ubisoft "own" games, that is the reason they are allowed to sell you licenses.
That being said, a lot of consumer laws apply to games because of the similarity with goods (especially those sold on a physical medium). But games aren't goods and never have been. You own the disc, but the information is only licensed by the "owner" to you. The fact that you could sell discs has something to do with a legal term called "first sales doctrine" (each country has something like this), which doesn't apply to purely digital "goods" in most cases as they cannot be "traded" and only copied. Depending on the country your in, an EULA prohibiting resale of boxed goods might be binding (Germany) or not (Poland). That is the reason more and more boxed games use Steam as DRM.
To come back to your question. GOG can never (without the consent of the rights owner that is) withdraw your license. If they go out of business you might lose the services they of on top of the license (online storage, support, etc), but the license remains.
Pretty much this.
Just to clarify - you don't "own" the game, but you DO "own" the licence. That means that the publisher is not entitled to withdraw the licence without good cause (in the legal sense of the term). That means that they cannot withdraw it at a whim. You are entitled to exhaust your rights on that particular copy of the game
Contrary to the claims presented by publishers, the transfer of "secondhand" shrink-wrapped software licences CANNOT be forbidden in many countries. Microsoft have found this out the hard way in Germany, and even the oft quoted Half-Life 2 ruling affirms this.
The problem that many people have with this is that they don't understand the difference between a licence and an access key, which are entirely different legal principles. An access key is provided with a licence. You cannot forbid the resale of packaged software in Germany or the UK, but the sale does not oblige the publisher to take any action.
So you can sell your copy of Half Life 2 in a box all you want, and Valve can't do a thing. What you can't do is demand that Valve provide you with a new key, and without that key, a boxed copy of Half Life 2 is pretty much useless. Steam is not compelled to actually transfer the licence from one account to another, and is within their rights to make the online services user account itself non-transferrable.
Seriously, German law is a fucking haven for eBay scammers.
(Of course, it gets hairy when you consider what happens to that guy with the useless Half Life 2 copy. They now have a useless, yet legal copy of Half Life 2, having bought the shrink-wrapped licence, and the seller has a registered, but illegal copy, having transferred it.)