We know, Rock Band 2 just hit shelves and we're already speculating about the instruments in Rock Band 3. But according to a posting on the Harmonix job board, the company is looking to hire a keyboard expert, which we can only assume means that a keyboard will be part of Rock Band 3. From the listing:
JOB OPENING: EXECUTIVE ASSISTANT-HARMONIX/Boston: 2+yrs admin exp. Strng communic & interprsnl sk; Proficient MS Word/Excel/PPT. Detail-oriented; str organ sk; fast-paced env. EOE/M/F/D/AAP.