If air southwest were to include jets into there fleet, then they would need to be able to operate safely out of Plymouth, as that is the main hub and core of the network. I doubt this would be anytime soon. They are very behind there "enviroment friendly dash 8's".
Exapnsion would be new Dash 8-300's.. With wow-c being tech and undergoing surgery at EXT, she could be replaced in the future as well