AFnord: I'm absolutely not saying that I want to go back to a time when games were far more expensive, but I do wonder what will happen to the (PC) market in the long run, if this goes on.
I think it will just find the equilibrium, one way or another. Game development costs are pushed down even more, some wannabe developers and publishers will exit the market in disgust and go back to flipping burgers, while some others continue...
The discussion seems to circle mostly on who is to blame for the dwindling PC game prices. IMHO it is because there are more and more commercial (indie) game makers nowadays, mostly thanks to the easy digital distribution. Part of the "problem" is that there is no restricted shelf space to sell older games either, like GOG demonstrates.
In the retail-only times, the restricted shelf space made sure there are only n number of games being sold at the same time. With digital distribution, there is no such restriction.
So, if we wanted to go back to the times of all new games costing fixed 50€ (no matter how much gameplay they offered or what were the development costs), it would mean most of the current PC game development teams or small publishers couldn't have ever even entered the market to try to compete with other developers/publishers. More competition means lower prices.
The old big publishers are the losers in this game (and the few old indie developers like the Spiderweb guy who is now miffed there are other indie developers out there in a price war with him), while the new players who finally have a chance to try to get their place in the sun are the potential winners.