I think there is still room to grow for the GOP in Appalachia. Take for example West Virginia. There is no reason for why such a state should be represented by two Democrats in the Senate.
There absolutely is: it's still one of the poorest states.
Poor doesn't equal Dem all the time though. Just look at the south. Yes most of the very poor are blacks but there are also many poor whites who vote republican. Really if you think about it the poor/rich divide is because of mostly race. Poor and rich whites have less of a divide.