There still exist desktop and screen that don't take much space. Sure, it might not be the best of what we can expect from a “gaming machine”, but it can still be better than a laptop. My gaming PC has the size of, approximately, two GC, and my screen is a little bit less large than my laptop when opened. Of course, when I had to move, they needed to be packed, but hey, so does laundry anyway.
Though if you really need mobility, as it seems to be the case for saerleiya, gaming laptop are relevant. Not the best conditions, but still better than… Well, “normal” laptops?
Or micro-consoles, if that ever get off. I had hopes for Ouya, actually. A tiny game machine that can fit in a pocket, just plug it on a monitor and play directly. Like a Game Hypercube !

Mostly independant games, probably. But with what a console like PSVita can do, it's not improbable that we see a tiny machine powerful enough to bring decent game while being absolutely mobile. (… Nintendo NX, maybe?)