I like the direction they're heading. Big fan of GOG.
I wonder if it's even possible for something like GOG to take a chunk out of Steam market share at this point, though. Valve is so entrenched in the psyche of the average PC gamer at this point, and rightly so. They've done a great job of creating a great platform and treating their customers well.
Not saying that these two can't coexist, but it seems unlikely, unless GOG truly does offer a significantly better experience, or they snag the rights for things that Steam doesn't have.