I honestly find it so strange that Steam itself hasn't landed onto Xbox/PS4. That just seems like such an intuitive move they should've done from the start TBH. Easier said than done, but if Steam has landed onto PC, OS X, and freaking Ubuntu, where the variation of machines that run those OSes varies from electric potato to supercomputers, I'm sure getting it right for consoles' specific specs won't be an issue.
Not all games would automatically work that way, obviously, but the Steamplay (or whatever it's called) stuff should.