blocking steam would be a huge mistake on msofts part...i think you want to exactly target the pc steam crowd that is used to these high prices because a >1000 usd price will cut the console crowd to half...
Even as a hybrid system, Project Helix may have more console characteristics than expected. GDC developers told insider Moore's Law Is Dead that Xbox exclusive games aren't ruled out. Microsoft could also exclude Steam from a storefront tailored to the new Xbox console.