Steam is accepting the bitcoin and that is not really known these days so that is pretty funny, the prices here on the forum are also much better so its logical that it will not really affect the market right now.
What price here on forum are you talking about? People selling games/keys on digital goods?
I think you can save more with steam discounts and promotions.
Well I dont know how they do it but it seems the prices in the forum are a little bit better, maybe they do something similar to pourse.io a website in which you can get a 15% discount by paying with bitcoin.