Bottom line: Misora/Harpnote is similar and/or somewhat based off of Meiru and Roll due to the need to create something familiar for us as the audience to identify with; if we assume that Misora is the new Roll, then we can adjust to the new series better and supposedly enjoy it more since we...
So they're going to finish the Tokyo arc with these OVAs and then what? A movie? will that really end it all? Will we get a ending that closes the story or will we be left with an open ending? So many questions, so few answers...