Harmonix may be set to announce their next game at the upcoming event Pax East. As of yet nothing is known of the upcoming title.
Those who looked closely at the description of the Pax panels would have noticed the following description.
“The panel will include game play examples from internal prototypes, honest discussion of our design process successes and failures, insight into how we create and test our games in development, and a synopsis of the design history of a title on public display for the very first time at the Harmonix booth.”
It looks promising that a new title may come out of the event, obviously its being kept under tight wraps but given the companies gaming history a music based game is certainly fair to say.