Yeah PC games I can continue to play, regardless of Valve going down. Valve go down, 90% of my library is more than likely acquirable on Demonoid.
PS Store/XBLA games? Not so much (maybe a few of the disc games may play in future if things like this PS3 hack prove to be useful, but setting up console to play those is also fiddly)
If I'm buying a PC game, and it's the same, or >£1 difference between disc n digital, I'm getting the disc. Means I save bandwidth, I can install whenever,(and wherever as far as HDD goes), and part of DD is in reducing the physical printing, packaging n shipping costs, the game should be cheaper. So if it isn't, I ain't rewarding that.
(Also in the "show your collection" kind of things it does sometimes suck that my shelf is short of a possible 70+ boxes)