Jobs is a salesman. Not a designer, nor an engineer, nor a programmer. You have to understand that before making assumptions that he has any ideas set in stone.
He says whatever it takes to sell whatever he's currently selling. If it doesn't have a certain feature, he'll tell you that feature is worthless or uses up too much battery... at least until his gizmo has the feature, and then it's suddenly a magical breakthrough.
He's also money savvy. On help forums there's been a slow but constant stream of posts about the volume rocker switches breaking and phones having to be replaced. The two button change might help solve that.
I have no idea if Apple would let the user assign any functions to the volume buttons. It might seem too WinMo-like to them. But it's getting obvious that the function overload of the single Home button is reaching ridiculous levels.
