Valve could suddenly dominate the mouse and keyboard market...

Valve's move into the console space is a no brainer. Computers have had a hard time telling consumers they can hook up to TV's, use gamepads, and play games.
Considering all they had to do was flesh out the Linux operating system and call it their own, develop an input device, and everybody else make the console.
I think they've already achieved their goal. More people buying games and software off of Steam.

Because of Valve's twin left and right layout, I think they can do monster damage in the left handed 10% world population. From a PC gamer background,
allowing users to change their hotkeys anyway they desire can have a dramatic effect on how you play the game. And play other games. For example, any game
where I cannot change "WASD / IJKL / Arrow Keys" to ASDF (Back/Forward/Strafe Left/Strafe Right) I simply won't play.

Any input has its' pros and cons. While I can easily do any advanced movement using ASDF touch typing in a first person shooter, trying to create a fireball
in a fighting game doesn't sound very easy. I would probably have to use a d-pad, control stick, or arcade stick. Valve's gamepad isn't taking away from
computer's input devices, only adding options to your play.

But if you cannot beat them, you have to join them...
The keyboard isn't going away. The mouse isn't going away. And this is the area I think Valve can do the most damage. Not by saying, "Hey n00bZ, use my
gamepad and get pwned in DotA 2!" But by using their gamepad to mount a keyboard and mount a mouse...

Keyboards:
If you take a QWERTY keyboard, split it down the middle, and plop down a gamepad...
1. Your thumbs do more than hit space or alt.
2. Your thumbs can suddenly control a mouse, arrow keys, etc. (As a n00b programmer, I'm always moving my right hand to the mouse or arrow keys)
3. Keyboards are more approachable by gamepad users.
4. Gamepads are more approachable to keyboard users.
5. Keyboards are everywhere... Business is good!

However, in reality? I have no idea. I don't even have $1 to my name to buy a candybar, let alone $99 to get on Steam GreenlighT. Our boy Gabe on the other
hand has millions if not billions to spend a few pennies on a prototype.

Mice:
The be all, end all, deathgrip of aiming and shooting... The all mighty mouse! While I highly doubt you could integrate a mouse underneath the gamepad,
I do think you could use an add-on to simply mount a mouse.
1. It's unlikely you even touch the lower backside of the gamepad, leaving an area viable for the mount.
2. Mice are made to be clawed, not held like a gun. Plus there's a lot of extra weight from the gamepad. However, you could use both hands instead of one.
3. Having an input device mount another input device just sounds too badass!

However, in reality? I don't have money for glue or duct tape to mount my X-BoX 360 gamepad on my mouse. Plus I'm a vegetarian. Can I even use glue or
duct tape?

Conclusion:
We play video games. Input matters! Your little casual gamepad is an incredible downgrade to the all mighty mouse and QWERTY! Thanks for letting me now play
crappy video games? Umm... Thanks? But I play first person shooters and first person swordplay slashers!

If you're into input as much as I am, check out my 1337 Board modification for Half-Life, Half-Life 2, and countless video games:
http://www.moddb.com/mods/elements-of-war/downloads/elements-of-war-1337-board-v8