In a recent interview, Jagex CEO Mark Gerhard talked to Gamasutra about how this exact approach gives the game an all-new feel that is more likely to draw in new players who might otherwise overlook it. He stated, "We could have called it RuneScape Next Age if we wanted to, and part of my thinking was, for people who haven't played this game in a year, it's going to be night and day. It's not a completely new game, but it's certainly a new experience." RuneScape 3 will have a more powerful audio engine, boosted visuals and a better draw distance, and upgrades to the UI, among other things.
Just like back with RuneScape 2, the plan is to maintain the RuneScape 3 moniker for a while, then drop the numeral and return to the original name again.