Even Gamestop knows physical media is on it's way out for gaming, and they're sticking their foot into both future possibilities.
Taking on Steam? Well...they do have a better chance than most. They already have publisher deals for physical sales, and they can run cross promos between physical/digital approaches. They've also gotten the scorn out of a lot of hardcore gamers for their shady business practices over the years, I know given an equal choice, I'd buy from Steam before GameStop.
Taking on OnLive? Well that depends on who gets playability on Android first. Mobile is one of the few places where something like cloud gaming could be useful. Get a device with an HDMI out and open Bluetooth (or USB host), hook it up to your TV, pair up a Bluetooth Mouse/KB or controller, and game on. It's a lot better than buying OnLive's stupid "console" plug, I really don't know why they haven't done it already.