The "Rest" of the Runeterra

Hey Riot, I got a SERIOUS question here. I feel, depending on your answer, it could really shake up the potential future of LoL. So have we seen ALL of Runeterra in terms of continents. I know Valoran is suppose to be like a supercontinent, but is Runeterra really only compromised of Valoran and Ionia? If not, then what other continents are there in Runeterra? Or, are you considering adding a new continent by using a "newly discovered" plot idea? Please let us know.