I don't think that the tablet or smartphone markets eat into the demographic that the PS3 and 360 have targeted. These people have smartphones already and maybe tablets, but they still buy the next CoD that comes out.
Fundamentally, it makes no sense for smartphones and tablets to steal share from the 20-30 male market. The whole point of those two devices is portability. You kill time while you're waiting for class to start or for the bus to come by playing 5 minutes of Angry Birds or checking e-mail.
You don't spend 2-3+ hours on the weekends playing Angry Birds or checking e-mail on your smartphone or tablet. That's not to say you don't touch those portable devices at home, but at worst, they're substituting laptops and desktops for internet surfing purposes.
Not to replace gaming.
Again, just look at the fundamental attributes of home consoles and smartphones/tablets, and the needs they satisfy. They don't overlap in a major way to substitute one another.
Now, if we're talking about people substituting 3DS's/Vita's with smartphones/tablets, or "casual" gamers seeing smartphones/tablets as an adequate substitute for Guitar Hero or Wii Fit, yeah, I'm on board with you guys.
