I personally don't think that this is a good idea as a business. By virtue of your (AFAIK) non-exsistant clout with the game development community and (AFAIK) the lack of several known games on your service, I think this will be a good exercise in several areas (like business management, software development, etc) but it's not something I would recommend anyone pay into.

Valve can do what it does because it has extablished games which are known to be successful driving the less popular games. You will have less popular games driving even less popular games and that is just going to be a bitch to do. Just because you are trying to tap the niche market of Indie Game developers doesn't mean that you can be a "Indie Steam"... it's going to take A LOT of work to get this up and running successfully... a lot more work than I think you imagine: The whole "If we make it, they will come" philosophy just doesn't work I'm afraid.

Again, I wish you luck and I hope you prove me wrong by being a glorious success!