Talking about GAMESPEAK, we know that it is going to be more natural and complex than Abe's games, but it is going to be very much easier to control.
Especulations
Gamespeak in Munch's Oddysee will use just two buttons, without "shift" keys,
that's for sure, Lorne said that in one of the latest interviews. I can't figure how its gonna work, maybe one of the buttons will work as a greetings button, and the other will work as a ask-for-help button.
It seems that the characters will be more aware of objects and other characters nearby. the relationships characters have to each other will drive the use of the sentences.
In the demo there is many examples:
The first time, Abe and Munch say "Hello". But after taht, Munch says "Hello" (he is looking at Abe) and Abe answers back saying "Hey, Munch". I suppose only one button was used here (the grettings button).
Munch also says to Abe: "Get'em!"(I suppose the ask-for-help or action button is used here) and it is the command Munch give to the fuzzles to make them attack enemies. But there is no enemies here, just Abe, and he answers "I don't think so..." followed by a low laugh from Munch, meaning "I'm just joking, dude", hehe.
when Abe gets to the closed gate, the guard of the gate is aware of Abe's presence. So, he says "hey Abe" and opens the gate to allow Abe and Munch to proceed.
I guess the analog buttons can be used to make characters yell to "all'ya!". If you just tap the button, he is going to say "hello". If you press it hard, it will yell, "al'ya!"
Again its all speculations.
I loved the way Abe answers Munch. He says: "Ok, dude!"

Hilarious.