Fictionvision: The market being flooded with bundles and promotions will lead to buyer fatigue and disinterest. Also, and I admit to being guilty of it, people try to keep up with them and eventually realize they have bought so many cheap games that they will never get around to playing them all. So people become less willing to buy the next thing that comes along as they know it will likely sit on the hard drive and never be played.
I reached this stage, but I think that for a lot of people (those who play more) that won't be the case. Even for me, I'm still buying the occasional game even though I hardly play. Although I did move from paying a significant sum for bundles to paying the minimum or close to it.
Still, I think that the market is big enough to sustain this for a while. I'm looking at Steam promotions or Steam Gifts giveaways, and people still buy or enter for games which you'd have thought that everyone already has.
As for Bastion, I'm not sure whether to buy it or wait for the Android release, where I'm more likely to play it.