BreathingMeat: But I think the question is: What will happen when GOG.com finally becomes unprofitable? Can gamers who have paid for content be assured that there is a permanent archive somewhere on the Internet where they can download or re-download their purchases?
This is one of the biggest questions about online distribution generally. At least GOG's stuff is DRM-free so people who have already downloaded their purchases will not find their games suddenly stop working...
Ultimately, I think this is going to be one for the courts. Digital information is such a departure from any other kind of material thing that determining what, exactly, the end user purchased and what responsibilities some publishers or distributors will have.
But GOG seems fairly straightforward. While they offer your game on the site for you to download for all time, there's absolutely nothing to suggest that the burden of storage or backup of what you've purchased is their responsibility.
Essentially, we've just cut out a lot of middle men. Instead of the publisher burning the game to a disc, packaging, and send it out to the store, we're instead downloading it to store however we see fit. You could burn it to a CD/DVD, or a hard drive, or 12,000 floppy disks, or memorize every single line of code.
Having the games here to download while GOG is here is a perk, but I think it would prove to be the burden of the buyer to view it as buying a product meant to be backed up by the end user; I think the fact that you can't play them directly from the site itself backs that assumption up.
The only times it would be tricky would be if GOG shut down in the middle of a download, or you bought like 30 games at once and then GOG closed without you being able to download any of them for backup.
I wonder what rulings, if any, courts have already made dealing with this. Might have to look that up.